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1
Han, Fa Sen. "Geotechnical Behaviour of Frozen Mine Backfills." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20250.
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This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.
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Reed, S. M. "Groundwater recovery problems associated with opencast mine backfills." Thesis, University of Nottingham, 1986. http://eprints.nottingham.ac.uk/11881/.
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The research outlined in this thesis is concerned with the environmental aspects of groundwater re-establishment as a consequence of surface mining. No principal effects which have been identified as being detrimental to the restored land area are as follows; i). The vertical and horizontal displacements of backfill materials following restoration, and ii). The pollution of groundwater from contact with weathered rockfill materials. The research into settlement has attempted to classify the types of movement which may occur within a backfill mass, in particular the differential movements which are of great importance to the stability of proposed structures or surface drainage. The field results from 10 opencast mine sites are presented, 3 of which were instrumented for detailed field investigations. It has been shown that backfill movements do not necessarily show similar trends under similar conditions, and reasons for this are proposed. A variety of instrumentation schemes have been devised to examine backfill displacements, both vertically and horizontally. Permeability testing has been conducted at different horizons the backfill mass in order to locate the zones of collapse settlement due to groundwater recovery. A critical review of the instrumentation utilised in the investigations is presented, with suggestions for improvement. Investigations into groundwater pollution have been devoted to examining the qualities of groundwater flowing into British surface mines and evaluating its likely reactions with fill materials. An insight into general groundwater pollution and treatment techniques is presented together with a critical analysis of their applicability, to British conditions. An investigation into water qualities in each of the six geographical regions of the opencast mining industry of Great Britain is detailed. Finally some suggestions for future research areas are indicated.
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Saidin, Fadzilah. "Behavior of geosynthetic reinforced soil walls with poor quality backfills on yielding foundations /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10124.
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Nasr, Mo'oud. "Numerical Analysis of the Effectiveness of Limited Width Gravel Backfills in Increasing Lateral Passive Resistance." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2530.
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Two series of static full-scale lateral pile cap tests were conducted on pile caps with different aspect ratios, with full width (homogeneous) and limited width backfill conditions involving loose sand and dense gravel. The limited width backfills were constructed by placing a relatively narrow zone (3 to 6 ft (0.91 to 1.83 m)) of higher density gravel material adjacent to the cap with loose sand beyond the gravel zone. Test results indicated that large increases in lateral passive resistance could be expected for limited width backfills. The main focus of this study is to assess the contribution of plane strain stress effects and 3D geometric end effects to the total passive resistance mobilized by limited width backfills, using soil and pile cap properties associated with the field tests. For this purpose, the finite element program, PLAXIS 2D was used to investigate the static plane strain passive behavior of the full-scale tests. To validate the procedure, numerical results were calibrated against analytical results obtained from PYCAP and ABUTMENT. The analytical models were additionally validated by comparison with measured ultimate passive resistances. The calibrated model was then used to simulate the passive behavior of limited width gravel backfills. Parametric studies were also executed to evaluate the influence of a range of selected design parameters, related to the pile cap geometry and backfill soil type, on the passive resistance of limited width backfills. Numerical results indicated that significant increases in passive resistance could be expected for long abutment walls where end effects are less pronounced and the geometry is closer to a plane strain condition. Comparisons between measured and numerical results indicated that using the Brinch-Hansen 3D correction factor, R3D, as a multiplier to the plane strain resistances, will provide a conservative estimate of the actual 3D passive response of a pile cap with a limited width backfill. Based on results obtained from the parametric studies, a design method was developed for predicting the ultimate passive resistance of limited width backfills, for both plane strain and 3D geometries.
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Fredrickson, Amy. "Large-Scale Testing of Passive Force Behavior for Skewed Bridge Abutments with Gravel and Geosynthetic Reinforced Soil (GRS) Backfills." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5513.
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Correct understanding of passive force behavior is particularly key to lateral evaluations of bridges because plastic deformation of soil backfill is vital to dissipation of earthquake energy and thermally-induced stresses in abutments. Only recently have studies investigated the effects of skew on passive force. Numerical modeling and a handful of skewed abutment tests performed in sand backfill have found reduced passive force with increasing skew, but previous to this study no skewed tests had been performed in gravel or Geosynthetic Reinforced Soil (GRS) backfills. The goal of this study was to better understand passive force behavior in non-skewed and skewed abutments with gravel and GRS backfills. Prior to this study, passive pressures in a GRS integrated approach had not been investigated. Gravel backfills also lack extensive passive force tests.Large-scale testing was performed with non-skewed and 30° skewed abutment configurations. Two tests were performed at each skew angle, one with unconfined gravel backfill and one with GRS backfill, for a total of four tests. The test abutment backwall was 11 ft (3.35 m) wide, non-skewed, and 5.5 ft (1.68 m) high and loaded laterally into the backfill. However, due to actuator loading constraints, all tests except the non-skewed unconfined gravel test were performed to a backfill height of 3.5 ft (1.07 m). The passive force results for the unconfined gravel test was scaled to a 3.5 ft (1.07 m) height for comparison.Test results in both sets of backfills confirmed previous findings that there is significant reduction in passive force with skewed abutment configurations. The reduction factor was 0.58 for the gravel backfill and 0.63 for the GRS backfill, compared to the predicted reduction factor of 0.53 for a 30° skew. These results are within the scatter of previous skewed testing, but could indicate that slightly higher reduction factors may be applicable for gravel backfills. Both backfills exhibited greater passive strength than sand backfills due to increased internal friction angle and unit weight. The GRS backfill had reduced initial stiffness and only reached 79% to 87% of the passive force developed by the unreinforced gravel backfill. This reduction was considered to be a result of reduced interface friction due to the geotextile. Additionally, the GRS behaved more linearly than unreinforced soil. This backfill elasticity is favorable in the GRS-Integrated Bridge System (GRS-IBS) abutment configuration because it allows thermal movement without developing excessive induced stresses in the bridge superstructure.
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Pruett, Joshua M. "Performance of a Full-Scale Lateral Foundation with Fine and Coarse Gravel Backfills Subjected to Static, Cyclic, and Dynamic Lateral Loads." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2317.
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Full-scale lateral load tests were performed on a pile cap with five backfill conditions: no backfill, densely compacted fine gravel, loosely compacted fine gravel, densely compacted coarse gravel, and loosely compacted coarse gravel. Static loads, applied by hydraulic load actuators, were followed by low-frequency, actuator-driven cyclic loads as well as higher frequency dynamic loads from an eccentric mass shaker. Passive resistance from the backfill significantly increased the lateral capacity of the pile cap. Densely compacted backfill materials contributed about 70% of the total system resistance, whereas loosely compacted backfill materials contributed about 40%. The mobilized passive resistance occurred at displacement-to-height ratios of about 0.04 for the densely compacted gravels, whereas passive resistance in the loosely compacted materials does not fully mobilize until greater displacements are reached. Three methods were used to model the passive resistance of the backfill. Comparisons between calculated and measured responses for the densely compacted backfills indicate that in-situ shear strength test parameters provide reasonable agreement when a log-spiral method is used. Reasonable agreement for the loosely compacted backfills was obtained by either significantly reducing the interface friction angle to near zero or reducing the soil's frictional strength by a factor ranging from 0.65 to 0.85. Cracking, elevation changes, and horizontal strains in the backfill indicate that the looser materials fail differently than their densely compacted counterparts. Under both low frequency cyclic loading and higher frequency shaker loading, the backfill significantly increased the stiffness of the system. Loosely compacted soils approximately doubled the stiffness of the pile cap without backfill and densely compacted materials roughly quadrupled the stiffness of the pile cap. The backfill also affected the damping of the system in both the cyclic and the dynamic cases, with a typical damping ratio of at least 15% being observed for the foundation system.
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Broomfield, Derek Chad. "Liquefaction potential of paste backfill." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ52879.pdf.
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Aldhafeeri, Zaid. "Reactivity of Cemented Paste Backfill." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38111.
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Mining has been one of the main industries in the course of the development of human civilization and economies of various nations. However, every industry has issues, and one of the problems the mining industry has faced is the management of waste, especially sulphide-bearing tailings, which are considered to be a global environmental problem. This issue puts pressure on the mining industry to seek alternative approaches for tailings management. Among the several different types of methods used, cemented paste backfilling is one of the technologies that offers good management practices for the disposal of tailings in underground mines worldwide.
Cemented paste backfill (CPB) is a cementitious composite made from a mixture of mine tailings, water and binder. This technology offers several advantages, such as improving the production and safety conditions of underground mines. Among these advantages, CPB is a promising solution for the management of sulphidic tailings, which are considered to be reactive materials (i.e., not chemically stable in an atmospheric condition) and the main source of acid mine drainage, which constitutes a serious environmental challenge faced by mining companies worldwide. Such tailings, if they come into direct contact with atmospheric elements (mainly oxygen and water), face oxidation of their sulphidic minerals, thus causing the release of acidic drainage (i.e., acid mine drainage) and several types of heavy metals into surrounding water bodies and land.
Therefore, the reactivity of sulphidic tailings with and without cement content can be considered as a key indicator of the environmental behavior and durability performance of CPB systems. For a better understanding of the reactivity, it is important to investigate the influencing factors. In this research, several influencing factors are experimentally studied by conducting oxygen consumption tests on different sulphidic CPB mixtures as well as their tailings under different operational and environmental conditions. These factors include time, curing temperature, initial sulphate content, curing stress, mechanical damage, binder type and content, and the addition of mineral admixtures. In addition, several microstructural techniques (e.g., x-ray diffraction and scanning electron microscopy) are applied in order to understand the changes in the CPB matrices and identify newly formed products.
The results reveal that the reactivity of CPB is affected by several factors (e.g., curing time, initial sulphate content, ageing, curing and atmospheric temperature, binder type and content, vertical curing stress, filling strategy, hydration and drainage, etc.), either alone or in combination. These factors can affect reactivity either positively or negatively. It is observed that CPB reactivity decreases with increasing curing time, temperature (i.e., curing and atmospheric temperatures), curing stress, binder content, the addition of mineral admixtures, degree of saturation, and the binder hydration process, whereas reactivity increases with increases in sulphide minerals (e.g., pyrite), initial sulphate content, mechanical damage, and with decreased degrees of saturation and binder content. The effect of sulphate on the reactivity of CPB is based on the initial sulphate content as well as curing time and temperature. It is concluded that the reactivity of CPB systems is time- and temperature-dependent with respect to other factors. Also, binders play a significant role in lowering CPB reactivity due to their respective hydration processes.
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Latifpour, Moozar Kasra. "Non-destructive appraisal of paste backfill." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79242.
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This thesis explores the possibility of using both miniature reflection (MSR-IE) and Ultrasonic (PUNDIT) techniques for the appraisal of paste backfill.The use of paste backfill is gaining popularity, however various technical, environmental and regulatory constraints complexify the study of its behaviour. There are various laboratory experiments available for the appraisal of this material; however the results do not necessarily correspond to its in-situ response. The main objective of this experimentation is to evaluate the quality of the fill by the study of its P-wave velocity, hence establish a relationship between the curing-time, strength and P-wave velocity of the material. This preliminary analysis in the field of mining demonstrates the possibility of finding an easy, reliable and cost effective in-situ method of appraising paste backfill.
Given the complexity of the research project, the work focuses on correlating the quality of the paste fill, with the MSR-IE and PUNDIT systems, in a laboratory environment. The results demonstrate the potential of the MSR-IE investigation on Paste backfill and the near future possibility of in-situ testing with this method.
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Winter, M. G. "The measurement of reinstatement backfill properties." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6541/.
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The Home Committee Report, published in 1985, identified the need for the reinstatement of service trench backfill to be performed to a higher and more reliable standard. This end was perceived as desirable, not only to improve road quality and safety, but also to increase the protection afforded to utility apparatus, thereby reducing the number of excavations required for its repair and replacement. The replacement of existing method specifications with a performance specification, based on the testing of an appropriate property of the reinstated material, is one possible means of improving the quality of reinstatement works. The Clegg meter is finding increasing usage for the purpose of compaction measurement. This device is simple to use and measures the decceleration response of a mass in collision with the ground surface. The decelartaion response is characterised by the Impact Value. The sampled volume is, however, very small in relation to the volume of material compacted and, for full evaluation, each compacted layer must be individually tested prior to the placing of the subsequent layer. The ideal test would be non-intrusive and operable from the final surface of the granular backfill; wave transmission velocity measurements are thus a potential technique. The propagation of sinusoidally excited Rayleigh-type surface waves is identified as the most promising method of measurement for reinstatement backfill quality. Experimental measurements of particle displacement at depth lend credence to the classical assumption that the depth of propagation of Rayleigh-type surface waves is equal to one-half the wavelength (z = γ/2).Included in this thesis is a review of the salient aspects of reinstatement works and a presentation of the necessary theory of wave propagation. The experimental results presented relate to tests on two sand materials compacted using different levels of compactive effort in all above-ground laboratory based trench and also to tests conducted on a crushed limestone aggregate under field conditions. Results from a short programme of field-based case studies are also presented. In addition to the surface wave velocity and Impact Value results, values for dry density and CBR are also presented. The data generally show a good correlation with compactive effort, whether defined simply as the number of passes/layer (N(_p)) or by a new parameter, the ratio of N(_p) to the mean layer thickness (N(_p)/h). Sensitivity analyses indicate that the Impact Value is a more sensitive measure of the degree of compaction than are either the surface wave velocity or the dry density. Conversion of the surface wave velocity results to shear modulus values, using measured density values, gives a sensitivity to compactive effort that is broadly comparable to that of the Impact Value. A novel technique for the analysis of Rayleigh-type surface wave attenuation data is presented. This allows the calculation of the material attenuation coefficient while obviating the need for potentially erroneous estimates as to the state of the attenuation curve, close to the source of vibration, to be made.
11
O'Neill, Mark A. "Creep settlement of opencast mine backfill." Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20148/.
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The extraction of a significant amount coal in the United Kingdom has over the last four or so decades been made using opencast mining methods. This method involves large-scale excavation to reach the coal seams (with depths often exceeding 100m). Following extraction various forms of restoration have been employed, including backfilling the mine void with material excavated in order to extract the coal. This backfilling was frequently undertaken in an uncontrolled fashion. In recent years it has been more usual to engineer the restoration such that further development of the site can take place. However, settlement remains the major obstacle to development. One mode of settlement commonly encountered on restored sites is creep settlement. Further, on older sites whose restoration was, most probably, undertaken in an uncontrolled way, the potential for creep settlement. is the major obstacle. Creep settlement is understood to be that component of total settlement which, in a coarse granular soil, takes place under conditions of constant stress. It is generally accepted to occur linearly with the decadic logarithm of time. This study investigates the phenomenon from the visualisation of the granular particle mechanics. The technique used for the visualisations is computed tomography (CT), a technique which is common in medical diagnostics but has rarely been exploited in soil mechanics and never at the scale employed in the study. The use of CT supplements a programme of high quality, large scale laboratory testing, which models typical opencast coal mine backfill. The testing programme has revealed that compaction and the diagenesis of the source materials have a significant effect on the creep rate. Further, that the creep rate is defined in the most part by the aggregation of small or minor movements rather being dominated by large or major movements.
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Bell, Sarah Beth. "WHEN BRAIN STIMULATION BACKFIRES." UKnowledge, 2019. https://uknowledge.uky.edu/psychology_etds/159.
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tDCS brain stimulation does not always work in the intended direction. It has been found to sometimes worsen behavior rather than improve it. A preliminary study shows that people high on sensation-seeking and lack of premeditation were prone to reverse effects of tDCS on performance on a Stop Signal Task. Both of these constructs are related to dopamine levels. Study 2 seeks to intentionally cause a reverse effect of tDCS by increasing participants’ dopamine levels via caffeine. There was not a significant interaction between tDCS and caffeine on errors on the Stop Signal Task in this study. However, other factors interacted with tDCS and caffeine including lack of premeditation. This two study package suggests the effects of tDCS are variable across individuals, with personality and neurochemistry both affecting behavioral outcomes of tDCS.
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Zhu, Zheming 1965. "Analysis of mine backfill behaviour and stability." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84453.
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Stable mine backfill is necessary for safe working conditions, maximum ore recovery and underground and surface stability. Due to the fact that cement costs can be a significant part of the operating costs in large underground mines, the consumption of cement (or binder) should be minimized. Therefore, developing a safe and economical backfilling method for the large underground mining operations is very significant.In this thesis, first laboratory tests and in-situ tests are implemented to determine backfill material properties and backfill stress distribution. The laboratory tests include high sulphide paste fill property tests and layered backfill tests. Second, a backfill finite element model is presented and it is validated by the results of laboratory tests and in-situ tests. Finally, by using this model, the following subjects are studied, (1) backfill stress distribution; (2) influences of backfill material properties and dimensions on backfill stability; (3) stress distribution of layered backfill; (4) optimum layered backfill. The results show that: (a) The variation of backfill material properties is quite large, the compressive strength of the layered backfill model is much higher than that of the non-layered backfill model, and the backfill vertical stress is much less than that anticipated by the formula, rhogH; (b) During the process of adjacent pillar recovery, the minor principal stress inside a backfill is tensile, and this tensile principal stress causes backfill failure and spalling near the exposed surfaces. The spalling size progressively increases with the height of the exposed surface, and a sliding zone creates and leads to backfill collapse; (c) Optimum backfill material should be high elastic modulus, high Poisson's ratio and low density. Optimum backfill size should be large depth and small width; (d) For layered backfill, no sliding zone occurs during the process of adjacent pillar recovery, so layered backfill can improve backfill stability. The optimum layered backfill should consist of strong layers distributed evenly with thicknesses of 1~2m and weak layers 2~2.5 times the thickness of the strong layers. This can save binder consumption by about 11%.
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Newman, Philip. "The preparation and transportation of paste backfill /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61309.
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Paste backfill has recently emerged in the Canadian mining industry as a potential solution to some of the problems regarding the waste disposal of mine tailings. Surface disposal is costly and its potential harm to the environment is incalculable.Besides waste disposal paste backfill also produces a stronger fill resulting in less dilution, less cement consumption and less clean up costs. These savings can only be realized with an accurate implementation of the new technology.
Presented is an overview of the current state of this emerging technology and the available equipment required for the preparation and transportation of paste backfill. It is hoped this work will provide the reader with a thorough grounding in paste backfill and enable him/her to understand that although large savings are possible the technology is still unproven within the context of the Canadian mining industry and further work is required before paste backfill becomes common practice.
Economic analyses are also presented regarding the different applications of paste at either existing or new mineral developments. Results from strength tests carried out as part of paste backfill feasibility projects are presented and show the increase in uniaxial compressive strength associated with an increase in slurry concentration. (Abstract shortened by UMI.)
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Parrish, Brandon R. "Geotextile wrap-face wall using marginal backfill." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4575.
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Thesis (M.S.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.
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Zeni, Marilia Abrão. "Caracterização de backfill cimentado na mina Aguilar." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/143712.
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Com a crescente diminuição de recursos minerais e o alto custo envolvido na construção da estrutura de uma mina, a recuperação máxima possível de uma jazida vem se tornando fundamental. Para isso além da escolha do método de lavra ter a necessidade de ser feito cautelosamente, é possível lançar mão de métodos adicionais de recuperação, como por exemplo, a recuperação de pilares. Essa pesquisa foi baseada na determinação da caracterização do enchimento (backfill cimentado) utilizado nas câmaras vazias que possibilita a posterior recuperação dos pilares. A caracterização do enchimento é composta da determinação da resistência simples do backfill necessária para que o enchimento cumpra com seu objetivo, desenvolvimento da classificação granulométrica ótima para os agregados e dosagem de cimento e água para alcançar a resistência proposta. A metodologia desenvolvida para obter a nova caracterização é composta de várias etapas que incluem pesquisas em campo e trabalhos em laboratório. Primeiramente, foram obtidos através de análise em campo os parâmetros de dosagem de cimento e classificação granulométrica dos agregados já utilizados na planta de fabricação do enchimento, bem como sua resistência correspondente. Em seguida definições teóricas da dosagem de cimento ideal e classificação granulométrica ótima foram realizadas com base na resistência à compressão simples que foi identificada como necessária para cumprir com as solicitações geomecânicas do maciço rochoso, então posteriormente, a nova caracterização definida teoricamente foi posta à prova através da confecção de corpos de prova de backfill, seguido de execuções de ensaios de compressão. Durante a primeira etapa da metodologia, já se pôde identificar que os agregados possuíam um alto índice de partículas tamanho argila que estavam afetando os resultados de resistência obtidos com a caracterização empregada inicialmente. A partir disso se optou por construir a curva granulométrica ótima sem essa fração. A resistência à compressão simples calculada de 2,69 MPa, foi obtida com base no planejamento de longo prazo que prevê a total recuperação dos pilares existentes na mina. Dessa maneira toda a área que será minerada foi considerada como um único bloco. Finalmente, foi identificada a dosagem de cimento sendo de 4% em peso, que juntamente com a granulometria ótima é capaz de alcançar os valores esperados de resistência. Para que o planejamento da produção da mina durante os próximos anos de vida útil seja efetivamente cumprido, o enchimento deverá prover à mina estabilidade geomecânica local a nível de câmaras abertas com paredes verticais de backfill estáveis e também estabilidade global a nível de contato entre níveis e galerias de acesso. Isso somente será alcançado se a nova caracterização for corretamente aplicada.As a consequence of the ongoing reduction of mineral resources and the high cost involved in the construction of a mine, the maximum recovery of a mineral deposit becomes a fundamental issue. Therefore, besides the need of caution on the choice of the mining method, it is possible to make use of additional recovery methods, such as the recovery of pillars. This research was based on the determination of the characterization of the fill (cemented backfill) used in avoid stopes that allows the subsequent recovery of adjacent pillars. The characterization of the fill consists of determining the uniaxial compressive strength of the backfill required for an efficient filling, developing an optimal particle-size distribution for the aggregates and finding the cement-water ratio necessary to reach the desired resistance. The methodology developed to obtain the new characterization is comprised of several steps which include field work and laboratory tests. First, cement dosing parameters and particle size of the aggregates (already used at the filling manufacturing plant), as well as their corresponding strength, were obtained through analyses in the field work. Then, theoretical definitions of the ideal cement dosing and optimal particle-size analysis were carried out based on the uniaxial compressive strength that has been identified as necessary to comply with the geomechanical requests from the rock mass, and then later, the new theoretical characterization was tested by making backfill samples, followed by execution of compression tests. During the first stage of this methodology, it has been identified a high proportion of clay particle size for the aggregates, that have affected the strength results obtained from the characterization used initially. From this point, we decided to build the optimal particle-size curve without this fraction. Uniaxial compressive strength, calculated as 2.69 MPa, was obtained from the long-term planning that determines the full recovery of the existing pillars in the mine. In this way, the entire area to be mined was considered as a single block. Finally, the cement dosing has been identified as 4% by weight, which together with the optimal particle size, is able to achieve the expected strength values. In order to effectively fulfill the mine production planning over the next years of lifespan, the filling should provide the mine local geomechanical stability at open stopes level, with vertical walls of stable backfill, and also global stability at the contacts between levels and access galleries. This will only be achieved if the new characterization is correctly applied.
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Huang, Xin 1958. "An integrated decision support system for backfill design." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41614.
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Backfill design is a multi-level, data/information/expertise intensive procedure involving various professional fields. During the life cycle of mining design and operation, a series of decisions are made based on the knowledge and personal experience. The success of mining design depends largely on knowledge available, and how knowledge is managed and processed. This thesis presents a conceptual backfill design rationale in a systematic approach in terms of basic information needs and data flow. Based on this representation, an integrated decision support system for backfill design is introduced. The underlying system is based on the integration of traditional databases, expert systems, hypermedia, and logical programming concepts consisting of the following components: (1) user interface, which creates the model of tasks and the application environment; (2) hypermedia-based reference manual, which supports non-linear access to backfill design reference manual of various formats; (3) expert systems which solve certain tasks based on heuristic rules; and finally, (4) knowledge base management system which provides an efficient approach to manage and manipulate massive data of previous backfill operations. The integration of these components is achieved through a blackboard architecture. The early test of the prototype system shows that the basic objectives have been achieved to provide fast information access and certain decision makings.
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Hills, Christopher William Walter. "The examination and prediction of opencast backfill settlement." Thesis, University of Nottingham, 1994. http://eprints.nottingham.ac.uk/11501/.
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With ever increasing demands on land use large areas of land are being considered for development which due to past or present mining activities are covered by substantial depths of fill materials. The problem faced with the development of land infilled with open cast mining backfill is in predicting the behaviour of the fill upon development. To be able to design foundations suitable to withstand the movements that occur within opencast backfill or design a backfilling operation that produces land suitable for a proposed after development, a means of predicting backfill settlement is required. From the analysis of a considerable quantity of data collected from the monitoring of backfilling operations and backfill movement at a range of opencast coal sites located within the UK, the behaviour of opencast backfill has been examined and better understood. This information has enabled a method of predicting backfill settlement to be developed which has been subsequently implemented as a computer program running under the Windows operating system. Factors taken into consideration during the prediction process are the timing of backfilling operations, the compactive state of the backfill, the inundation of the backfill and the influence of surrounding material and a means of predicting differential settlement due to backfill heterogeneity is proposed. Examples are given demonstrating the significance of these factors upon settlement predictions made at a hypothetical site. Finally, a comparison is made between predicted settlements and those monitored at an actual site to demonstrate the validity of the method proposed.
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Blanchfield, Richard. "Volume change characteristics of opencast coal mine backfill." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480898.
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Ghirian, Alireza. "Coupled Thermo-Hydro-Mechanical-Chemical (THMC) Processes in Cemented Tailings Backfill Structures and Implications for their Engineering Design." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34605.
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The main result of underground mining extraction is creating of large underground voids (mine stopes). These empty openings are typically backfilled with an engineering cementitious material called cemented paste backfill (CPB). The main purpose of CPB application in underground mining is to provide stability and ensure the safety of underground openings, maximize ore recovery, and also provide an environmental-friendly means of underground disposal of potential acid generating tailings. CPB is a mixture of mine tailings, cement binder and water. CPB has a complex geotechnical behaviour when poured into mine voids. This is because of the different thermal (T), hydraulic (H), mechanical (M) and chemical coupled processes and interactions that take place in CPB soon after placement. In addition to these THMC behaviours, various external factors, such as stope geometry, drainage condition and arching effects add more complexity to its behaviour. In order to acquire a full understanding of CPB behaviour, there is a need to consider all of these THMC factors and processes together. So far, there has not been any study that addresses this research need. Indeed, fundamental knowledge of the THMC behaviour of CPB provides a key means for designing safe and cost-effective backfill structures, as well as optimizing mining cycles and productivity of mines. Innovative experimental tools and CPB testing methods have been developed and adopted in this research to fulfill the objectives of this research. In the first phase of the study, experiments with high columns are developed to study the THMC behaviour of CPB from early to advanced ages with respect to height of the column and curing time. The column experiments simulate the mine stope and filling sequence and provide an opportunity to study external factors, such as evaporation, on the THMC behaviour of CPB. However, an important factor is the overburden pressure from the stress due to self-weight that cannot be simulated through column experiments. Therefore, in the second phase of this study, a novel THMC curing under stress apparatus is developed to study the THMC behaviour of CPB under various pressures due to the self-weight of the CPB, drainage conditions, and filling rate and sequence. Comprehensive instrumentation and geotechnical testing are carried out to obtain fundamental knowledge on the THMC behaviour of CPB in different curing conditions from early to advanced ages. The results of these studies show that the THMC properties of CPB are coupled. Important parameters, such as curing stress, self-desiccation due to cement hydration, temperature, pore water chemistry, and mineralogical and chemical properties of the tailings, have significant influence on the shear strength and compressive strength development of CPB. Factors such as evaporation and drying iii shrinkage can also affect the hydro-mechanical properties of CPB. The curing conditions (such as curing stress, drainage and filling rate) also has significant impact on CPB behaviour and performance. The THMC interactions and the degree of influence of each factor should be included in designing backfill structures and planning mining cycles. This innovative curing under stress technique can be replaced the conventional curing of CPB (curing under zero stress and no THMC loadings), in order to optimize CPB mechanical strength assessment, increase mine safety and enhance the productivity.
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Masniyom, Manoon. "Systematic Selection and Application of Backfill in Underground Mines." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-4418234.
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The use of backfill in underground mining is increasing due to need for systematic backfilling of mine openings and workings to avoid surface damage, increase safety and contribution to sustainable mining. This study is to investigate backfill materials and new methods suited for systematic selection and application of backfill in underground mines. Laboratory tests were carried out on physical, chemical and mechanical properties of different backfill materials and mixtures thereof. Special attention was paid to materials generated as by-products and other cheaply available materials e.g. fly ash and FGD-gypsum from power plants, natural and synthetic anhydrite. The different material mixtures investigated can be used as a technically and economically viable backfill for underground mines. In summary, the systematic selection of backfill materials from by-products, mine waste and tailings from the mineral processing of mining industry and other industries were suited as a backfill material for test field in China coal fires and recommended for underground potash mines in Thailand.
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Piciacchia, Luciano 1959. "Field and laboratory studies of mine backfill design criteria." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74360.
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This work develops a backfill design procedure aimed to facilitate the optimization of an available mine material in order to meet target objectives in a particular mining role. This required the compilation and analysis of data on fill usage, established design procedures, physical and geomechanical properties, testing techniques and procedures, as well as behavioural modelling methods.A backfill classification system is proposed based upon size distribution. A series of design equations are presented which relate to this system. These equations represent the means by which backfill geomechanical behaviour can be related to physical properties. This is considered to be fundamental to an effective backfill design procedure. Derivation of the equations has been based upon analysis of data from a program of laboratory and in situ testing conducted in ten operating Canadian mines by the author, together with other published work.
The in situ testing required the development of a pressuremeter testing procedure novel to underground mining. The theoretical basis for the employment of pressuremeter data has been examined and behavioral equations have been developed to describe the deformation and stress history during a backfill material test. In addition two new equations have been developed for the analysis of pressuremeter data. The in situ data collected has been correlated with laboratory derived geomechanical data for the same backfill materials.
The geomechanical properties associated with the proposed backfill classifications have also been related to their influence on backfill behaviour in three mine backfill roles: free standing stability during pillar recovery in bulk mining methods; dynamic interaction with stope walls in rockburst prone ground; and ability to reduce stresses in highly stressed rock masses. This work has been based on new and established modelling methods and aims to provide insight into the effectiveness of the backfill classes in these roles of growing practical significance.
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Fadaei, Kermani Mehrdad. "An investigation into a new binder for hydraulic backfill /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112568.
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Over the last three decades, mine backfilling has progressively integrated into underground mining operations. The high stresses associated with mining at depth in the Canadian Shield, also requires innovative approaches to mine backfilling to withstand the loading both during and after mining operations. Not only new or modified minefill systems are required, but also new techniques are needed to increase the speed of the mining cycle for optimizing the mining operation. Three major purposes of mine backfill are known as (1) providing safe working condition, (2) maximizing ore recovery and (3) improving underground stability. Therefore, mine backfill has contributed greatly to the economics and environmental aspects of mining industry.In order to improve the mechanical behaviour of fill, cementitious materials are used. These cementitious materials are expensive. As a result the consumption of these cementitious materials has to be optimized and minimized in a way that the required strength is met. The objective of this research is to investigate a new type of backfill, which is known as gelfill. Gelfill binders usually consist of alkali activators such as sodium silicate and the other cementitious materials. Sodium silicate has been used in waste treatment and activation of artificial pozzolans such as blast furnace slag and fly ash.
The work presented in this thesis is to evaluate the use of sodium silicate in gelfill. Consequently, the influence of mixing time, mixing sequence and curing time are studied on gelfill and silica sand hydraulic backfill. Various tests including unconfined and confined compressive strength were conducted in order to investigate the mechanical behaviour of samples. By conducting mercury intrusion porosimetery (MIP) and scanning electron microscopy (SEM), microstructure and mineralogical properties of specimens were studied.
The result of this thesis demonstrates that gelfill compared with silica sand hydraulic backfill has better mechanical properties. In addition, other variables, including: mixing time and sequence, have a significant effect on gelfill.
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Bull, Andrew. "Temperature Dependence of the Leachability of Cemented Paste Backfill." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38866.
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Underground mining is a mineral acquisition technique that is critical to global economies, and human technological advancements. As shallow resource reserves are depleted, mine depths are increasing to accommodate global mineral demand. Increases in mine throughputs and excavation depths pose increased environmental concerns. Tailings surface disposal, and underground mine support are two considerable environmental and geotechnical factors of concern in current day mining. Underground waste disposal has been adopted by the mining industry in many forms. Cemented paste backfill (CPB) is a common best management practice developed to tackle these two specific resource industry related issues worldwide. CPB is a cement-stabilized material composed of tailings, water, and hydraulic binder. Tailings disposal areas on the earth’s surface are reduced by disposing of tailings in subsurface stopes that have been previously excavated. This increases underground safety by providing structural support to the mine. There are also economic benefits to this practice, as the additional support allows for adjacent pillars to be excavated. Although CPB greatly reduces tailings exposure to atmospheric elements, there are still underground environmental factors that must be considered with respect to environmental performance. CPBs are porous media, meaning they are susceptible to leaching of naturally occurring metals that are no longer in a stable condition as they were when incorporated in the parent rock. Arsenic and lead are metals of concern due to their association with many ore bodies. Leaching of these unstable metals may be influenced by the backfill curing temperature and the chosen hydraulic binder. Curing temperatures may be influenced by geographic location, local stope geology and depth, hydration and transport, among others. Hydraulic binders are chosen based on availability, cost, and desired mechanical properties of the paste. In this research, the effect of curing temperature and binder composition on the leachability of CPB are studied. ASTM C 1308 leaching protocol is used to determine the leachability of six CPBs. In addition, microstructural techniques (Powder X-Ray Diffraction, Mercury Intrusion Porosimetry, and Scanning Electron Microscopy) are used to relate the microstructural properties of the CPB to the leaching characteristics. Results reveal that CPBs cured with ordinary Portland cement (OPC) leach significantly less than CPBs cured with an OPC/Blast furnace slag (Slag) binder (50% blending ratio) as a result of CH consumption in slag hydration. Both CH and C-S-H are responsible for immobilizing arsenic in cement stabilized materials. OPC-CPBs contain greater relative quantities of CH, which aids in arsenic immobilization. Between the range of 2°C and 35°C OPC-CPB performed better at lower curing temperatures. Lower curing temperatures are favoured in OPC-CPB because the pore surface greater than the threshold pore diameter is reduced. Alternatively, OPC/Slag-CPB exhibited a decrease in cumulative mass leached at higher curing temperatures. The difference in cumulative mass leached by the OPC/Slag-CPBs is also related to the pore surface, and threshold pore diameter.
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Ting, Nai-Hsin 1964. "Earthquake-induced tilt of retaining wall with saturated backfill." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/17319.
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Vissotto, Júnior Lucas Alberto. "Análise tridimensional de mina subterrânea com ênfase na interação entre maciço e preenchimento (caso de estudo: mina Cuiabá)." reponame:Repositório Institucional da UnB, 2013. http://repositorio.unb.br/handle/10482/15754.
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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2013.Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2014-06-02T15:23:43Z No. of bitstreams: 1 2013_LucasAlbertoVissottoJunior.pdf: 10786095 bytes, checksum: 3f5b3f8971d2d1ae09a7d2b2066a4338 (MD5)
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Este trabalho apresenta uma análise tridimensional de mina subterrânea com ênfase na interação entre maciço rochoso e preenchimento (backfill), considerando o comportamento mecânico do maciço enquanto ocorre o progresso das escavações e da disposição com aumento da tensão confinante e endurecimento do módulo de deformabilidade. Foi realizado o monitoramento do caso de estudo da Mina Cuiabá e comparados os resultados com as modelagens tridimensionais. O tipo específico de lavra estudada foi o cut and fill com orientação sub vertical. Nas modelagens foi analisado o processo de endurecimento do modulo de deformabilidade do backfill, de acordo com a etapa do ciclo de lavra. Os resultados do monitoramento e das modelagens mostraram que a adoção pelo backfill contribui de modo ativo para a estabilidade e segurança da mina. O aumento da tensão confinante devido ao endurecimento do backfill aumentou a interação mecânica com o maciço. Um aspecto sócio ambiental importante relaciona-se ao preenchimento das escavações com rejeito que tendem a mitigar os impactos ambientais, principalmente pela considerável redução dos volumes de rejeitos dispostos em superfície. _______________________________________________________________________________________ ABSTRACT
This study presents a numerical and experimental three-dimensional analysis of the interaction rock mass / backfill, considering the mechanic behavior of rock mass, during the process of excavation and backfill disposal, with increase of the confining stress and the module deformability hardening. The study case of Mine Cuiabá was monitored and the results were compared with the three-dimensional models. The specific type of mine studied was the cut and fill with sub vertical orientation. In the simulations was considered the module of backfill deformability that varies according to the stage of the exploration cycle. The disposal via backfill technology was simulated and monitored, which the results showed a positive contribution with the stability and safety of mine. The increase of the confining stress due to the hardening of backfill deformability module improved the interaction rock mass and backfill. This study showed that the backfill disposal linked to underground exploration mine tends to mitigate the environmental impacts in the mine.
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Bouzaiene, Riadh. "On the flow mechanics of mine backfill slurries in pipelines." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28992.
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This thesis deals with the flow mechanics of hydraulic and high density mine backfill slurries in pipelines. Various empirical, rheological and mechanistic approaches are presented and analysed along with some aspects pertinent to experimental testing of backfill slurries.The main contribution of this work is, particularly, in the development of an analytical model to describe the flow and predict the pressure gradient of a class of high density backfill whose motion in pipelines follows the Plug Flow Model (PFM). The development of the model called for investigating the conditions required for establishing Plug Flow. It was found that mix proportioning procedures, similar to those found in the concrete industry, are key factors in obtaining Plug Flow.
Pressure drop was found to be a function of the thickness of the Bingham plastic annular layer surrounding the cylindrical core of aggregates. Analytical equations were proposed to solve for the thickness of this layer by considering the rheology of the mixture. Alternatively, the thickness of the annular layer may be estimated by considering the relative proportions of the mixture with respect to aggregates void content. The model offered pressure drop predictions in good agreement with published data. The proposed model may also serve as an alternative to Mooney's method, when dealing with the annular lubricating layer effect characterising mixtures in Plug Flow.
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Crawford, James R. "Backfill pressures within a reinstated trench, the Gatineau Field Project." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/MQ28414.pdf.
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Jones, Charles H., Mark Wigent, Jon Morgan, and Russ Beech. "A Synergistic Test Flight: Smart Sensors, EQDR and PCM Backfill." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577489.
Full textAbstract:
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CAThis is the story of three projects, which use three different research funding sources, coming together to demonstrate a small, but complete, instrumentation system that advances several technologies. The Onboard Smart Sensor (OSS) project is a Small Business Innovation Research (SBIR) project that incorporates IEEE 1451.4 sensors into an existing Common Airborne Instrumentation System (CAIS) based instrumentation system. These sensors are "smart" in that they can self-identify basic information via a Transducer Electronic Data Sheet (TEDS). The Enhanced Query Data Recorder (EQDR) is being developed under the T&E Science & Technology Spectrum Efficient Technology (S&T SET) portfolio. This recorder is based on the integrated Network Enhanced Telemetry (iNET) specifications. One of the objectives of iNET is to be able to query a recorder in real-time and transfer the request across a network telemetry link. The third project provides Pulse Code Modulation (PCM) backfill to compensate for dropouts. One of the envisioned applications enabled by the iNET architecture is the ability to provide PCM displays in the control room that do not have dropouts. This is called PCM Backfill. The basic scenario is that PCM is both transmitted (as it traditionally has been via serial streaming telemetry (SST)) and recorded onboard. When dropouts occur, a request over the telemetry network is made to the recorder (the EQDR in this case) and the dropped portions of the PCM stream are sent over the telemetry network to backfill the ground display. By adding a PCM-to- Ethernet/iNET bridge, the OSS and legacy instrumentation system can provide data to both the standard PCM and to the EQDR. Combined, this mini-system demonstrates a vision of having intelligence and networking ability across the entire instrumentation system – from sensor to display.
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Morgan, Jon, and Charles H. Jones. "PCM Backfill: Providing PCM to the Control Room Without Dropouts." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/577490.
Full textAbstract:
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CAOne of the initial control room capabilities to be demonstrated by iNET program is the ability to provide data displays in the control room that do not contain data dropouts. This concept is called PCM Backfill where PCM data is both transmitted via traditional SST and recorded onboard via an iNET compatible recorder. When data dropouts occur, data requests are made over the telemetry network to the recorder for the missing portions of the PCM data stream. The retrieved data is sent over the telemetry network to the backfill application and ultimately delivered to a pristine data display. The integration of traditional SST and the PCM Backfill capability provides both real-time safety of flight data side-by-side with pristine data suitable for advanced analysis.
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Goh, Chee Tiong. "The behaviour of backfill to shallow abutments of integral bridges." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270310.
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Snapp, Michael Andrew. "Electrical resistivity measurements of mechanically stabilized earth retaining wall backfill." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19771.
Full textAbstract:
Master of ScienceDepartment of Civil Engineering
Stacey Kulesza
In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 (“Standard Method of Test for Determining Minimum Laboratory Soil Resistivity”). AASHTO T 288-12 is designed to test a soil sample’s electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate. In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material’s bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.
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Crawford, J. James R. "Backfill pressures within a reinstated trench: The Gatineau field project." Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/4163.
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To the backdrop of shrinking municipal budgets and aging water distribution system infrastructure, the National Research Council of Canada undertook a joint research project with the City of Gatineau, PQ, to better understand the nature of backfill pressures acting through the reinstated trench and upon buried water pipe. This thesis first presents the general details of this joint project focusing on backfill temperature and pressure data for the period August 1994 to August 1996. These data are then analyzed leading to a description of the relationship between frost depth and backfill pressure. Contrary to experience, the trend that emerges, in the case of the Gatineau field site, is that pressure and frost depth are inversely related. Finally, problems associated with the data and related to instrumentation are explored with the objective of developing guidelines or recommendations for the development of future field research sites.
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Ito, Sei, Takeshi Honda, Toshihisa Tanaka, and Daiki Aoyama. "THE PERFORMANCE TEST OF AN INITIAL iNET-LIKE RF NETWORK USING A HELICOPTER." International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624257.
Full textAbstract:
Through the use of early iNET-prototype IP Transceiver technology, Kawasaki Heavy Industries,
Ltd. (KHI) has been able to communicate with a flight test vehicle. This technology provides a
two-way high-capacity communication that has not been achieved with conventional telemetry.
KHI has been authorized to use S-band IP Transceivers since 2014 in Japan. Then various
communication tests have been performed. Last year we presented the result of the performance
test of initial iNET-like RF network using a tethered aerostat at ITC. As the next phase, we have
a plan of the test using a helicopter. The test is going to be conducted in September. We will
present the results at ITC. This paper describes plans of the test which includes improved data
backfill techniques.
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Tsang, Chiu Ming. "Life-time analysis of continuous beam bridges with integral abutments using rheological models." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8609.
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Annor, A. "A study of the characteristics and behaviour of composite backfill material." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0031/NQ64497.pdf.
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Bozorgzadeh, Azadeh. "Effect of structure backfill on stiffness and capacity of bridge abutments." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3274986.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed October 2, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 260-265).
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Bowman, Charles H. "Geotechnical charcterization of coal refuse for use as a backfill material." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08182009-040343/.
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Hughes, Paul B. "Design guidelines : underhand cut and fill cemented paste backfill sill beams." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/47089.
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Difficult ground conditions negatively affect both mine production and the safety of underground workers. Underhand cut-and-fill mining is a potential solution to these issues. Discussions with mine sites revealed the use of sill beams in underhand cut-and-fill mining is not optimized. Optimization in ground support, development of in-situ strength test, and revisions of design standards are desired. Ultimately, the operations require the minimum cemented paste backfill (CPB) strength for a stable span.
Operational concerns were addressed by a multi-prong approach investigating stability of CPB sill beams using observational, experimental and analytical techniques. A case study approach summarizing the design of five mines utilizing underhand cut-and-fill with CPB is presented for different ground conditions. A historical study of span widths and beam strengths for the Stillwater mine is presented.
Laboratory testing determined the stress-strain behaviour of CPB. CPB follows a hyperbolic elastic loading path to peak stress followed by a strain-softening associated with the decay of the cohesion values. Additional testing found that cohesive and tensile strength values were on average 35 and 20 percent respectively of the unconfined compressive strength. This finding impacts sill beam design strengths as previous assumptions were conservative. Test database analyses from three mine sites found that sample size and location preparation has no effect on the strength of the sample. In-situ testing methods common in other industries were not practical with CPB; rather the in-situ strength can be represented by a site specific moisture content index relationship.
Review of current design methodology noted closure stresses were absent from the majority; a method was developed to assess closure for sill beam stability. The potential for critical failures were determined through a Monte Carlo probabilistic model. Methods reducing the risk of failure based on the simulation are investigated. Analysis found ground support does not improve the structural stability of the sill beam. Ground support keeps the beam intact: beam equations govern stability. The stability of sill beam in a seismic environment was analyzed based on the strain-energy density of the beam. The research concludes with a design guideline for CPB sill beams.
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Simmons, Andrew Ray. "Use of flowable fill as a backfill material around buried pipes." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2477.
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Thesis (M.S.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains viii, 152 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 87-91).
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Yap, Fook Liong. "The application of the discrete element method to integral bridge backfill." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/333184/.
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Expansion joints and bearings of conventional bridges are easily damaged and this commonly incurs high maintenance costs. The concept of the integral bridge was to reduce the maintenance costs by removing those joints. However, the thermally induced expansion-contraction of the bridge superstructure is transferred through the integral bridge’s abutments due to lack of expansion joints. Seasonal thermal cyclic displacement of the integral abutment cyclically loads the bridge backfill material. It has been observed that the lateral earth pressure behind an integral abutment increases as a result of the cyclic loading. Previous studies attribute this increase in lateral pressure to the densification of the backfill material. Granular flow was suggested to have occurred displacing the particles to form a denser and therefore stiffer matrix. An alternative suggestion was that the particles reoriented to form a stiffer matrix that wasn’t necessarily denser. The objective of this research is to explore the behaviour of integral abutment backfill at a micromechanical level by utilising the discrete element method (DEM) and possibly verify these suggested causes of earth pressure build-up behind an integral abutment. DEM models of four granular materials consisting of different particle shapes were tested with 100 cycles of strain. The results indicate that densification occurred for all samples, but the build-up of horizontal pressure did not occur for the more rounded samples. It was further suggested that the particle shape in combination with the change in coordination number closely replicate the behaviour of the sample’s horizontal stress. Particle reorientation and displacements were observed to be small for samples of non-circular particles. Particle activity is concentrated in the smallest particles within the material. It is concluded that the build-up of horizontal stress is caused by the increase in particle contacts due to particle reorientation and not densification.
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Van, Tonder Warren Deon. "Centrifuge modelling of permeability in a heterogeneous coal mine backfill sequence." Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/57291.
Full textAbstract:
Opencast mining has been and continues to be a favoured method for the extraction of the
vast coal reserves in the Highveld of South Africa. Previously backfilled and restored open cast
areas are generally zoned for agricultural uses, but with growing pressures on land use, such
areas are increasingly being considered for the expansion of infrastructure and regional
development. Understanding the backfill permeability and hydraulic behaviour is therefore an
important component in defining the land use restrictions placed on a previously backfilled
area. Centrifuge modelling provides a means of better understanding the hydraulic behaviour
and measuring the permeability of opencast backfill under controlled laboratory conditions.
Based on a preselected backfill prototype, an appropriate centrifuge model was developed.
Using miniature pore pressure transducers, the pore pressures were measured at discrete
locations in the model during falling head tests in a geotechnical centrifuge. Using the
measured volumetric discharge, spacing between the transducers and the measured pore
pressures, the permeability of the backfill was calculated. Due to polarized opinions on the
scaling of permeability in a centrifugal field, a control model was tested at 1g and 23g to
validate this scaling law. It was demonstrated that the respective permeabilities calculated at
1g and 23g were effectively the same and that it is in fact the hydraulic gradient that is scaled
N times in the centrifuge. Knowing this allowed the calculated centrifuge permeabilities to be
directly related to the prototype represented by the model. To determine the accuracy of the
centrifuge model, the results of field percolation tests were compared to the results of an
analogous centrifuge model. There was no correlation between the results and it was not
considered meaningful to compare the results, as the model and percolation test site
(prototype) conditions differed significantly. To simulate the preselected prototype backfill
sequence, a model configuration that represented the geometry and material properties of the
prototype was tested at 35g (half scale) and 70g (full scale) in the centrifuge. The results of
the centrifuge model were used to make reasonable predictions on the long term permeability
and hydraulic behaviour of the backfill prototype. It was found that the permeability of the
backfill is likely to decrease over time due to consolidation settlement. The bottom of the backfill
sequence is expected to have the lowest permeability and the top is likely to maintain a higher
permeability. It was further demonstrated that the horizon interfaces acted as flow restrictors
and resulted in poor vertical permeability between the horizons in the backfill sequence.
Overall the centrifuge methodology provided a unique and efficient means of modelling the
long term permeability and hydraulic behaviour of the backfill sequence.Dissertation (MSc)--University of Pretoria, 2015.
tm2016
Geology
MSc
Unrestricted
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Cui, Liang. "Multiphysics Modeling and Simulation of the Behavior of Cemented Tailings Backfill." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36145.
Full textAbstract:
One of the most novel technologies developed in the past few decades is to convert mine wastes into cemented construction materials, otherwise known as cemented tailings backfill (CTB). CTB is an engineered mixture of tailings (waste aggregates), water and hydraulic binders. It is extensively used worldwide to stabilize underground cavities created by mining operations and maximize the recovery of ore from pillars. Moreover, the application of CTB is also an environmentally friendly means of disposing potential acid generating tailings underground. During and after its placement into underground mine excavations or stopes, complex multiphysics processes (including thermal, T, hydraulic, H, mechanical, M, and chemical, C, processes) take place in the CTB mass and thus control its behavior and performance. With the interaction of the multiphysics processes, the field variables (temperature, pore water pressure, stress and strain) and geotechnical properties of CTB undergo substantial changes. Therefore, the prediction of the field performance of CTB structures during their life time, which has great practical importance, must incorporate these THMC processes. Moreover, the self-weight effect, water drainage through barricades, thermal expansion and chemical shrinkage can contribute to the volumetric deformation of CTB. Consequently, CTB exhibits unique consolidation behavior compared to conventional geomaterials (e.g., soil). Furthermore, the consolidation processes can result in relative displacement between the rock mass and CTB. The resultant rock mass/CTB interface resistance can reduce the effects of the overburden pressure or the vertical stress (i.e., arching effect). Hence, a full understanding, through multiphysics modeling and simulation of CTB behaviors, is crucial to reliably assess and predict the performance of CTB structures. Yet, there are currently no models or tools to predict the fully coupled multiphysics behavior of CTB. In this Ph.D. study, a series of mathematical models which include an evolutive elastoplastic model, a fully coupled THMC model, a multiphysics model of consolidation behavior and a multiphysics model of the interaction between the rock mass/CTB interface are developed and validated. There is excellent agreement between the modeled results and experimental and/or in-situ monitored data, which proves the accuracy and predictive ability of the developed models. Furthermore, the validated multiphysics models are applied to a series of engineering issues, which are relevant for the field design of CTB structures, to investigate the self-desiccation process, consolidation behavior of CTB structures as well as to assess the pressure on barricades and the strength development in CTB structures. The obtained results show that CTB has different behaviors and performances under different backfilling conditions and design strategies, and the developed multiphysics models can accurately model CTB field behavior. Therefore, the research conducted in this Ph.D. study provides useful tools and technical information for the optimal design of CTB structures.
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Aref, Khosrow. "A study of the geotechnical characteristics and liquefaction potential of paste backfill /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75878.
Full textAbstract:
A significant amount of work has been directed toward the improvement of mine backfill during the past decades. Paste backfill was recently introduced as a superior support system for underground hard rock mining operations. The aim of this study is to examine the applicability of paste backfill to full scale underground operations.The Tailspinner system was developed to produce paste backfill. This system dewaters the full stream tailing material from approximately 55% to 24% water content. These densified tailings are mixed with cement prior to placement in a stope.
The utilization of paste backfill possesses several economical and mechanical advantages. Paste backfill however, contains a high proportion of ultra fine solids, which results in a material of very low permeability. Hence, the question of liquefaction susceptibility of this material becomes important.
This investigation is directed primarily towards the behavior of paste backfill when subjected to static and dynamic loading conditions. The main objective of this study was to evaluate the liquefaction resistance of paste backfill. However in order to accomplish this goal, studies also have to be made into the static characteristics. The behavior of both reconstituted and undisturbed samples were investigated.
A comprehensive testing program on paste backfill samples was carried out. The static testing program was conducted to define the strength and deformation characteristics of paste backfill. The influence of cement and water content on static properties of paste backfill were investigated.
The liquefaction resistance of paste backfill was evaluated based on several mechanisms. The results of a comprehensive study on the liquefaction potential of paste backfill are presented. The effect of variation in void ratio, confining pressure and cement content on the liquefaction resistance of backfill were investigated.
The in situ tests were conducted on a paste backfilled stope at Dome Mines. A unique in situ testing program using a piezometer friction cone was carried out. This enabled the determination of the geotechnical characteristics and the evaluation of the liquefaction potential of paste backfill. The dynamic properties of the paste backfill were also investigated through a series of blasts adjacent to the backfilled stope. The resultant energy transfer and peak particle velocity transmitted through the rock and paste backfill was monitored with a series of accelerometers.
The liquefaction analyses show that liquefaction resistance increases with increasing cement content and decreasing void ratio. Various curves were developed to present the influence of the above parameters for paste backfill application. The laboratory and in situ results obtained in this study should improve the understanding of backfill properties for design and operational purposes.
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Mada, Hemachandar. "Numerical modeling of buried pipes with flowable fill as a backfill material." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4262.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains x, 157 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 128-132).
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Crawford, Anika. "Beneficial reuse of Baltimore dredged sediments as vertical cutoff wall backfill material." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1473.
Full textAbstract:
Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Hsieh, Tsung-Ying, and 謝宗穎. "Numerical Analysis of Wrap-faced GRS Retaining Wall with Gravel Backfills." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bbnkda.
Full textAbstract:
碩士國立雲林科技大學
營建工程系
106
Geosynthetic-reinforced soil (GRS) retaining wall backfilled with gavels has been gradually applied to permanent or important structures such as railroads or road embankments. In view of the above, this study uses a finite difference method based program FLAC (Fast Lagrangian Analysis of Continua) as a numerical tool to simulate the behavior of wrap-faced GRS retaining wall with gravel backfill. The dimensions of the numerical model wall were 186 cm (width) × 112 cm (height). In the numerical model, the wrapped facing with soil bag was viewed as an integrated unit and was respectively assigned as several types of materials, such as an elastic or a Mohr-Coulomb one. Besides, the gravel backfill and reinforcement were respectively modelled as a strain-softening material and a cable element. The behavior of interface between reinforcement and gravel backfill was simulated by introducing proper parameters for the so-called grout element next to the cable element. Numerical results shows that a Mohr-Coulomb type soil bag is more relevant for the numerical model. A calculating step more than 20,000,000 is recommended in the numerical analysis with a target footing vertical displacement equal to 100 mm. The calculated footing bearing capacity can be enhanced if a larger value of so-called kbound parameter of the cable element is adopted. However, further research focusing on calibrating the reasonable value of the above kbound in GRS retaining wall with gravel backfill is needed.
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Chiang, Han-Yu, and 江瀚宇. "Numerical Analysis of Wrap-faced GRS Retaining Wall with Sandy Soil Backfills." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/k5feub.
Full textAbstract:
碩士國立雲林科技大學
營建工程系
106
In this study, a series of finite difference method (FDM) based numerical analysis on the behavior of wrap-faced GRS retaining with sandy soil backfills was performed. The dimensions of the numerical model wall were 186 cm (width) × 112 cm (height). In the numerical test, the backfill were modelled as Mohr-Coulomb plastic or strain-softening material, and soil bag of wrapped facing were respectively simulated using strain softening model, Mohr-Coulomb plasticity model and elastic isotropic model. Besides, the soil-reinforcement interaction was modelled as cable element with an adjustable shear stiffness and sliding strength. It is found that for the numerical model having strain softening type backfill and Mohr-Coulomb plastic type soil bag, using the inferred plane strain friction angle based on the direct shear test results, the simulated behavior is most closed to the experimental data of model test.
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Wu, Jen-Chung, and 吳仁忠. "Properties of CFBC Ash and Pulverized Coal Bottom Ash used for Backfills." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/11659809535202825794.
Full textAbstract:
碩士國立臺灣海洋大學
材料工程研究所
96
Circulating fluidized bed combustion (CFBC) ash and pulverized coal (PC) bottom ash were mixed following the designed proportions. Specimens were tested to evaluate the engineering properties in accordance with the suitable specifications. Test variables include the mix proportions and preloading and compressive strength test, soil compaction test, direct shear test, CBR test, triaxial pervious test and SEM observation were conducted in order to verify the feasibility of CFBC ash mixtures used as for backfill materials or controlled low strength materials. Test results indicate (1) optimum moisture content of six mixtures decreased with an increase in PC bottom ash and increased as preloading increased; (2) cohesion and internal friction angle increased as loading increased; (3) when the mixing ratio (by weight) of CFBC ash to PC bottom was 1:1.5, CBR (56 strokes) reached the highest value(2.84), and all the test mixtures were satisfied the ASTM requirements of bearing capacity for subgrade according to the CBR testing results; and (4) coefficient of permeability increased by with an increase in PC bottom ash; (5) the 12-hour and 28-day compressive strengths of blended ash mixtures (besides mix F) satisfied the specified values of CLSM according to ACI specifications.
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Wang, kai-Ming, and 王凱民. "Effect of CFBC Ash used for Controlled Low Strength Material (CLSM) for Backfills." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/d869ye.
Full textAbstract:
碩士國立臺灣海洋大學
河海工程學系
105
This research is for the purpose of discussing domestically uses the circulation type fluidized bed (Circulating Fluidized Bed Combustion, after CFBC) burns has the industry sideline product substitution potential of for the concrete packing material, appraised the controllability low intensity backfill material (CLSM) allocated proportion burns the incineration in the present project use using the circulation fluid bed the latent use, allocated proportion of in the controllability low intensity backfill material uses the common plumbing engineering backfill use the F level ash or completely replaces take the part the use as the CFBC ash, reaches to in the allocated proportion to pick the different proportion to substitute directly the thin aggregate packing material experiment minute to mix the result newly. This research the controllability low intensity backfill material allocated proportion in the cement, the water consumption and the hydrogel compared to in does not change under the principle, the CFBC ash don't by 0%, 20%, 40%, 60%, 80% and 100% proportion substitutes for the first wife to fly the ash F of level compared to the use, with in addition directly uses 0% in the CLSM allocated proportion, 10%, 20%, 30%, 40% and 50% CFBC ash amount used acts as the thin aggregate packing material, carries on various allocated proportions design to mix CLSM to collapse the fluidity, to fall newly sinks the quantity and the different stadium the compressive strength test. This research trial result showed that,Newly mixes in the controlled low strength material allocated proportion the packing material to use CFBC the ash substitution part F level to fly the ash, 28th the days compressive strength it finally request are can conform to the Executive Yuan Publicworks Committee construction summary standard 03377th chapter of stipulation to be smaller than 80kgf/cm2 to stipulate, demonstrated utilizes the CFBC ash in controlled low strength material should for have the potential to perform converting into resources of sideline product the utilization.