Relevant bibliographies by topics / Backfills

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Backfills'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Backfills"

1

Sample-Lord, Kristin M., Wenjie Zhang, Shan Tong, and Charles D. Shackelford. "Apparent salt diffusion coefficients for soil–bentonite backfills." Canadian Geotechnical Journal 57, no. 5 (May 2020): 623–34. http://dx.doi.org/10.1139/cgj-2019-0058.

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Apparent diffusion coefficients, Da, were measured for two soil–bentonite (SB) backfills characteristic of those used in SB vertical cutoff walls for subsurface control of contaminant migration. The base soils for the backfills comprised either a natural lean clay or sand–bentonite mixtures. The base soils were mixed with 5% bentonite–water slurry to obtain a slump of 125 mm, resulting in total bentonite contents ranging from 4.76% to 7.31%. Values of Da for sodium chloride were measured using a recently developed dialysis-leaching test method. The Da values for the clay–bentonite and sand–bentonite backfills ranged from 2.5 × 10−10 to 5.3 × 10−10 m2/s and from 1.4 × 10−10 to 8.1 × 10−10 m2/s, respectively. Values of Da for both backfills increased with increasing average salt concentration in the specimen (Cave). Values of Da decreased by ≤50% with increasing backfill bentonite content. For all Cave values, the clay backfills exhibited lower Da than the sand–bentonite backfills, likely due to additional fines from the lean clay. Results of this study enhance understanding of solute diffusion through SB cutoff walls, as well as support future use of the dialysis-leaching test method to measure diffusion properties of SB backfills.
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Tang, Yanan, Weidong Song, and Jianxin Fu. "Damage constitutive model of stratified cemented backfill based on coupling macroscopic and mesoscopic deformations." E3S Web of Conferences 194 (2020): 05024. http://dx.doi.org/10.1051/e3sconf/202019405024.

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The mechanical properties and stress-strain relationship of cemented backfills with different stratified structure have a direct effect on the mining-filling cycle and the mining of adjacent pillars. To obtain the stress-strain evolution curves, the uniaxial compressive strength tests were performed on backfills with stratified numbers of 0, 1, 2 and 3. The deformation of stratified backfill under the compressive load is regarded as a compound of closed deformation of the macroscopic stratified structure and elastic deformation of material. The damage constitutive model of cemented backfills with different stratified structure are established by considering the influence of compacted section. Comparative analysis reveals that the calculated curve based on the established sectional damage constitutive model conforms well to the trial curve. The maximum closed strain of the structural plane has a more significant effect on the mechanical properties of backfill. In the Weibull distribution, with the increase of the parameter m, the peak strength of backfill gradually increases and then reaches to a certain value, and the stress-strain curve gradually becomes steeper, which shows that m is a reflection of the concentration level of micro-unit strength distribution in the backfill..
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Mitchell, Robert J. "Centrifuge model tests on backfill stability." Canadian Geotechnical Journal 23, no. 3 (August 1, 1986): 341–45. http://dx.doi.org/10.1139/t86-048.

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The 6 m diameter, 30 g-tonne geotechnical centrifuge at Queen's University is described. Results from eight model tests, carried out on plain cemented sand samples representing mine backfills, are presented. These data show that the stable prototype backfill heights obtained from centrifuge tests exceed the failure heights predicted from unconfined compression testing by factors averaging about 1.8. This factor is explained by a combination of geometrical and behavioural effects. Still photographs of typical backfill failures in the centrifuge are included and these indicate that unacceptable ore dilution and recovery costs would be associated with the prototype failures in plain cemented tailings backfills. Key words: geotechnical centrifuge, mine backfill, model tests, cemented sand.
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Fan, Ridong, Yuling Yang, and Songyu Liu. "Impact of In Situ Soil in Soil-Bentonite Cutoff Wall Backfill on Compressibility and Hydraulic Conductivity." Advances in Civil Engineering 2021 (January 19, 2021): 1–12. http://dx.doi.org/10.1155/2021/9350604.

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Soil-bentonite cutoff walls, consisting of excavated in situ soil and bentonite as backfills, are used extensively as vertical barriers for groundwater pollution control. Sand mixed with high-quality natural sodium bentonite (NaB) is commonly used as a research object to investigate the hydraulic and compression properties of soil-bentonite backfills. However, pure sand could rarely be found in real conditions, and natural NaB may not be available readily in some countries such as China, India, and Turkey. This paper presents a comprehensive laboratory investigation on the compressibility and hydraulic conductivity (k) of soil-bentonite backfills created by simulated in situ soil and low-quality sodium activated calcium bentonite (SACaB). The simulated in situ soils are prepared using sand-natural clay mixtures with sand to natural clay mass ratios ranging from 0.5 to 6.0, and the bentonite content (BC) in the base mixture ranges from 0 to 15%. The result indicates that BC dominates the compression index (Cc) of the backfill, and a unique relationship between void ratio at effective vertical compression stress of 1 kPa and compression index is proposed for various types of soil-bentonite backfills. An increase in either BC or clay size fraction (CF) in simulated in situ contributes to reducing k, but the impact of CF in simulated in situ soil on k tends to be insignificant for backfill with BC higher than 6%. A new characteristic parameter based on the concept of void ratio of bentonite (eb), named apparent void ratio of clay size fraction (eC), is developed for predicting soil-bentonite backfills created by in situ soils and bentonites with various contents.
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Deng, Hongwei, Yao Liu, Weiyou Zhang, Songtao Yu, and Guanglin Tian. "Study on the Strength Evolution Characteristics of Cemented Tailings Backfill from the Perspective of Porosity." Minerals 11, no. 1 (January 15, 2021): 82. http://dx.doi.org/10.3390/min11010082.

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At present, the filling mining method is widely used. To study strength evolution laws of cemented tailings backfill (CTB) under different curing ages, in the experiment, mine tailings were used as aggregates, ordinary Portland cement (PC32.5) was used as cementing materials, and different additives (lime and fly ash) were added to make filling samples with the solids mass concentration at 74% and the cement-sand ratios 1:4, 1:6 and 1:8. Based on the nuclear magnetic resonance (NMR) technology, the porosity test of filling samples with curing ages of 3 d, 7 d and 28 d was carried out, and the uniaxial compressive strength test was carried out on the servo universal material testing machine. The relationship between the uniaxial compressive strength and porosity of backfills and the curing age in the three groups was studied, and change laws of the porosity variation and strength growth rate of backfills were analyzed. Based on the variation in porosity, the strength evolution model of the CTB under different curing ages was established, and the model was fitted and verified with test data. Results show that the uniaxial compressive strength, porosity, porosity variation, and strength growth rate of the three groups of backfills gradually increase with the increase of the curing age, the porosity of backfill basically increases with the decrease of the cement–sand ratio, and the porosity of backfill decreases with the increase of the curing age. Porosity variations and relative strength values of the three groups of backfills under different cement-sand ratios obey an exponential function, and the two have a good correlation, indicating that the established filling strength evolution model can well reflect strength evolution laws of the CTB with the change of curing age.
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Yang, Yu-Ling, Krishna R. Reddy, Wen-Jie Zhang, Ri-Dong Fan, and Yan-Jun Du. "SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater." International Journal of Environmental Research and Public Health 17, no. 1 (January 6, 2020): 370. http://dx.doi.org/10.3390/ijerph17010370.

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This study investigated the feasibility of using sodium hexametaphosphate (SHMP)- amended calcium (Ca) bentonite in backfills for slurry trench cutoff walls for the containment of lead (Pb) contamination in groundwater. Backfills composed of 80 wt% sand and 20 wt% either Ca-bentonite or SHMP-amended Ca-bentonite were tested for hydraulic conductivity and sorption properties by conducting laboratory flexible-wall hydraulic conductivity tests and batch isothermal sorption experiments, respectively. The results showed that the SHMP amendment causes a one order of magnitude decrease in hydraulic conductivity of the backfill using tap water (1.9 to 3.0 × 10−10 m/s). Testing using 1000 mg/L Pb solution resulted insignificant variation in hydraulic conductivity of the amended backfill. Moreover, SHMP-amendment induced favorable conditions for increased sorption capacity of the backfill, with 1.5 times higher retardation factor relative to the unamended backfill. The Pb transport modeling through an hypothetical 1-m-thick slurry wall composed of amended backfill revealed 12 to 24 times of longer breakthrough time for Pb migration as compared to results obtained for the same thickness slurry wall with unamended backfill, which is attributed to decrease in seepage velocity combined with increase in retardation factor of the backfill with SHMP amendment. Overall, SHMP is shown to be a promising Ca-bentontie modifier for use in backfill for slurry trench cutoff wall for effective containment of Pb-contaminated groundwater.
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Sobhi, Mohamed Amine, Li Li, and Michel Aubertin. "Numerical investigation of earth pressure coefficient along central line of backfilled stopes." Canadian Geotechnical Journal 54, no. 1 (January 2017): 138–45. http://dx.doi.org/10.1139/cgj-2016-0165.

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The earth pressure coefficient K, defined as the horizontal to vertical normal (effective) stresses ratio (σh/σv), is a key parameter in analytical solutions for estimating the stresses in backfilled stopes. In the case of vertical stopes, the value of K has sometimes been defined using the at-rest earth pressure coefficient K0, while others have applied Rankine’s active earth pressure coefficient Ka. To help clarify this confusing situation, which can lead to significantly different results, the origin and nature of the at-rest and Rankine’s active coefficients are first briefly recalled. The stress state in backfilled stopes is then investigated using numerical simulations. The results indicate that the value of K can be close to Ka for cohesionless backfills along the vertical central line (CL) of vertical stopes, due to sequential placement and partial yielding of the backfill. For inclined stopes, simulations show that the ratio between the minor and major principal stresses (σ3/σ1) along the CL in the backfill, which differs from σh/σv, can also be close to Ka. A simple expression is shown to represent the horizontal to vertical stresses ratio σh/σv (= K) along the CL of such inclined stopes well. A discussion follows on the effects of backfill properties and simulation approach.
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Siddiqua, Sumi, James Blatz, and Greg Siemens. "Evaluation of the impact of pore fluid chemistry on the hydromechanical behaviour of clay-based sealing materials." Canadian Geotechnical Journal 48, no. 2 (February 2011): 199–213. http://dx.doi.org/10.1139/t10-064.

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The results of an experimental program undertaken to evaluate the impact of pore fluid salinity on the hydromechanical performance of light and dense backfill materials are presented. Light and dense backfills are engineered barrier materials that are being examined in the Canadian concept for storage of spent fuel in a deep geological repository. The current research investigates the impact of pore fluid chemistry on the swelling, compressibility, stiffness, and hydraulic conductivity parameters of light and dense backfills that are required as material parameters for analysis and design. In these tests, pore fluid chemistry was selected to represent groundwater within potential host units including granite and limestone rock. Results show that the performance of light backfill is significantly affected by changes in pore fluid chemistry. The swell potential of light backfill decreases with increasing salinity of the solution. The hydraulic conductivity decreases with increasing effective montmorillonite dry density and specimens saturated with saline solution have higher hydraulic conductivity than those saturated with distilled water. Conversely, the behaviour of dense backfill is governed mainly by the crushed granite component and therefore changes to the pore fluid chemistry have relatively little effect. Results of dense backfill tests confirm the material performance as a sealing material.
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Zhao, Jack Q., Balvant B. Rajani, and Lyne Daigle. "Thermal performance of trench backfills used for frost protection of water service lines." Canadian Geotechnical Journal 38, no. 1 (February 1, 2001): 161–74. http://dx.doi.org/10.1139/t00-085.

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This paper describes the thermal performance of different configurations of trenches using various trench geometries and backfill and insulation materials. A limited number of laboratory tests were conducted to confirm the thermal properties of the backfills reported in the literature. The frost protection of water service is measured in terms of the number of days it takes for the frost front to reach the depth of water service lines under sustained subzero surface temperatures. The study specifically included typical granular materials used within the City of Ottawa (formerly the Region of Ottawa-Carleton), but the findings can be equally applied to other urban areas in Canada where the surficial terrain is rocky. The thermal analyses of the trenches were conducted using the finite element method that appropriately represents phase changes when the temperature falls below the freezing point of water. The analyses indicate that the use of sandwich insulation is ineffective, and that latent heat of backfill and native soils has a great impact on the frost protection of water service lines. A list of possible trench depths with different backfills and their thermal performance is provided.Key words: backfill, thermal performance, frost penetration, water service, finite element analysis.
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Siddiqua, Sumi, James Blatz, and Greg Siemens. "Experimental study on the performance of light and dense backfills." Canadian Geotechnical Journal 48, no. 2 (February 2011): 214–25. http://dx.doi.org/10.1139/t10-057.

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Numerical modeling is a cost-effective and important approach to examine the long-term performance of engineered materials. However, to identify the appropriate constitutive model for a particular material it is necessary to measure physical properties in a laboratory. Laboratory experiments provide the data from which the input parameters for the selected model can be interpreted. This paper studies the mechanical behaviour of two clay-based sealing materials — light backfill and dense backfill — recommended for use in disposal of nuclear waste in a proposed Canadian repository. Test specimens of light and dense backfills were saturated in a triaxial cell and then subjected to specified isotropic and shearing stress paths to measure consolidation and shear characteristics. The triaxial results are interpreted in a critical state context. The light backfill results suggest that it has similar stress–strain behaviour to a bentonite–sand buffer, which has a similar composition, but different preparation procedures and design requirements. Results from testing of dense backfill indicate that it is a much stiffer and stronger material than light backfill. Dense backfill is expected to provide mechanical support to the used-fuel container and other sealing components of the Canadian repository, and the mechanical behaviour of dense backfill satisfies these requirements.
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More sources

Dissertations / Theses on the topic "Backfills"

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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.
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Books on the topic "Backfills"

1

Zohrabi, M. The permeability of structural backfills. Crowthorne: TRL Limited, 2001.

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DiGioia, A. M. High-volume ash utilization in roadways, embankments and backfills: An update. S.l: s.n, 1987.

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Brady, K. C. Performance of an experimental reinforced earth structure using soft chalk backfills. Crowthorne: Ground Engineering Division, Structures Group, Transport and Road Research Laboratory, 1990.

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Singh, R. N. The effect of groundwater reestablishment on the settlement of opencast mine backfills in the United Kingdom. S.l: s.n, 1985.

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Beauchamp, Kevin. High modulus backfill. Sudbury, Ont: Laurentian University, School of Engineering, 1993.

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Dygard, Thomas J. Backfield package. New York: Morrow Junior Books, 1992.

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Dygard, Thomas J. Backfield package. New York, NY: Puffin, 1993.

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Murphy, Michael Keenan. High density paste backfill. Sudbury, Ont: Laurentian University, School of Engineering, 1994.

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Backfield in motion. Riverdale, MD: La Caille Nous Pub. Co., 2002.

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Boldt, C. M. K. Backfill properties of total tailings. Pgh. [Pittsburgh], PA: U.S. Dept. of the Interior, Bureau of Mines, 1989.

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Book chapters on the topic "Backfills"

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Krumhansl, James L., Patrick V. Brady, and Peng-Chu Zhang. "Soil Mineral Backfills and Radionuclide Retention." In Geochemistry of Soil Radionuclides, 191–209. Madison, WI, USA: Soil Science Society of America, 2015. http://dx.doi.org/10.2136/sssaspecpub59.c9.

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Oliver, P. H., and D. Landriault. "The convergence resistance of mine backfills." In Innovations in Mining Backfill Technology, 433–36. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211488-54.

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Mitchell, R. J. "Stability of classified tailings backfills containing reinforcements." In Innovations in Mining Backfill Technology, 237–46. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211488-29.

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Piciacchia, L., M. Scoble, and J. M. Robert. "Field studies by full displacement pressuremeter in mine backfills." In Innovations in Mining Backfill Technology, 247–56. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211488-30.

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Cortes, Douglas D., Ali Nasirian, and Sheng Dai. "Smart Ground-Source Borehole Heat Exchanger Backfills: A Numerical Study." In Springer Series in Geomechanics and Geoengineering, 27–34. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99670-7_4.

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Gupta, Ashish, Vinay Kumar Chandaluri, Vishwas A. Sawant, and Sanjay Kumar Shukla. "Development of Design Charts for the Dynamic Active Thrust from c–ϕ Soil Backfills." In Lecture Notes in Civil Engineering, 111–22. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0562-7_13.

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Lai, Jiunnren, Ming-Hong Lai, and Chiung-Fen Cheng. "Assessing the Bearing Capacity of Backfills by Stress Wave Velocity and Cone Penetration Resistance." In Infrastructure Sustainability Through New Developments in Material, Design, Construction, Maintenance, and Testing of Pavements, 109–16. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-79644-0_9.

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Yang, Yu-Ling, Krishna R. Reddy, Yan-Jun Du, and Ri-Dong Fan. "Sorption of Lead to Slurry Trench Cutoff Wall Backfills Comprised of SHMP-Amended Ca-Bentonite." In Proceedings of the 8th International Congress on Environmental Geotechnics Volume 2, 537–43. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2224-2_66.

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Yang, Yu-Ling, Yan-Jun Du, Krishna R. Reddy, and Ri-Dong Fan. "Adsorption of Cr(VI) onto SHMP-Amended Ca-Bentonite Backfills for Slurry-Trench Cutoff Walls." In Proceedings of GeoShanghai 2018 International Conference: Geoenvironment and Geohazard, 434–41. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0128-5_48.

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Jiang, Zhe-Yuan, Run Zhang, Xian-Lei Fu, Jia-Lei Wan, Shuang-Jie Li, Yu-Ling Yang, and Yan-Jun Du. "Investigation of Hydraulic Conductivity of SHMP Amended Soil-Bentonite Backfills Exposed to Lead-Impacted Groundwater." In Developments in Sustainable Geomaterials and Environmental Geotechnics, 1–13. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-79647-1_1.

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Conference papers on the topic "Backfills"

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Rudland, D., G. Wilkowski, and B. Rothwell. "The Effects of Soil Properties on the Fracture Speeds of Propagating Axial Cracks in Line Pipe Steels." In 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10086.

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The ductile fracture resistance of newer line pipe steels is of concern for higher grade/strength steels and higher-pressure pipeline designs. Although there have been several attempts to make improved ductile fracture arrest models, the model that is still used most frequently is the Battelle Two-Curve Ductile Fracture Arrest Model, which incorporates the gas-decompression behavior with the fracture toughness of the pipe material to predict the minimum Charpy energy required for crack arrest. For this model, the effect of backfill on the propagating crack fracture speeds is lumped into one empirically based “backfill coefficient,” which does not distinguish different soil types or strengths. Some modifications to this backfill coefficient have been proposed for frozen soil as a function of moisture content, and for water backfill for offshore applications, but no attempt has been made to quantify the effects of soil type, total density or strength on the fracture speeds of propagating cracks in line pipe steels. This paper presents the results from a series of small diameter pipe burst tests that were conducted with different soil backfills. The soils’ moisture content, density, and strength were fully characterized in situ and in the laboratory. In addition, fracture speed data in both unbackfilled and backfilled conditions were recorded. The comparison of the change in fracture speed as a function of soil type, moisture and strength gives valuable insight into the effects of soil on the arrest of running ductile fractures in line pipe materials.
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Klimašauskas, Mindaugas, and Valentinas Šaulys. "Drainage Trench Conductivity and Biogenic Materials Retention." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.081.

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In the work, the effectiveness of hydrosystem functioning, when the filtration characteristics of the drainage trench backfill are improved by admixing lime materials, is analysed after a 28-year period of use. The tests of effec-tiveness of hydrosystem functioning were carried out in the test object of Raseiniai district, Kalnujai. The drainage was installed in the drying systems and the filtration characteristics of trench backfills were improved by admixing the lime material. Analysing the maximum comparative debits of drainage in the control drying systems in the period of spring and autumn 2016 (0.006 and 0.190 ml/s m, respectively) as well as comparative debits in the period of spring and autumn (0.015 and 0.311 ml/s m, respectively) in the drainage, which filtration characteristics of trench backfills were improved by admixing chalkly materials (0,6% ground mass), the results were better by 60.0 and 38.9%, respec-tively. Assessing the drainage system effectiveness indexes of 2012, 2013 and 2016 with the reliability of 95%, it can be stated that the effectiveness of drainage functioning, when the lime materials were used for the improvement of the filtration characteristics of drainage, did not change essentially after a 28-year period of use.
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Belem, Tikou, Andries Fourie, and Martin Fahey. "Time-dependent failure criterion for cemented paste backfills." In Thirteenth International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2010. http://dx.doi.org/10.36487/acg_rep/1063_13_belem.

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Yang, Yu-Ling, Yan-Jun Du, Krishna R. Reddy, and Ri-Dong Fan. "Hydraulic Conductivity of Phosphate-Amended Soil-Bentonite Backfills." In Geo-Chicago 2016. Reston, VA: American Society of Civil Engineers, 2016. http://dx.doi.org/10.1061/9780784480144.053.

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Mashayekhi, Meysam, Victor N. Kaliakin, Christopher L. Meehan, Michael T. Adams, and Jennifer E. Nicks. "Numerical Modeling of Structural Backfills for Transportation Infrastructure." In Eighth International Conference on Case Histories in Geotechnical Engineering. Reston, VA: American Society of Civil Engineers, 2019. http://dx.doi.org/10.1061/9780784482124.003.

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Li, Bo, Xiangwu Zeng, and Haiyan Ming. "Seismic Response of Retaining Wall with Anisotropic Backfills." In Earth Retention Conference (ER) 2010. Reston, VA: American Society of Civil Engineers, 2010. http://dx.doi.org/10.1061/41128(384)68.

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Yang, Yuling, Yanjun Du, Ridong Fan, Mingli Wei, and Zuobo Chen. "Apparent Viscosity of Phosphate Dispersant-Amended Soil-Bentonite Backfills." In Geo-Shanghai 2014. Reston, VA: American Society of Civil Engineers, 2014. http://dx.doi.org/10.1061/9780784413432.002.

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Fan, R. D., Y. J. Du, S. Y. Liu, and Z. B. Chen. "Compressibility and Hydraulic Conductivity of Sand/Clay-Bentonite Backfills." In Geo-Shanghai 2014. Reston, VA: American Society of Civil Engineers, 2014. http://dx.doi.org/10.1061/9780784413432.003.

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Malusis, Michael A., and Gemmina Di Emidio. "Hydraulic Conductivity of Sand-Bentonite Backfills Containing HYPER Clay." In Geo-Congress 2014. Reston, VA: American Society of Civil Engineers, 2014. http://dx.doi.org/10.1061/9780784413272.183.

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Zamiran, Siavash, and Abdolreza Osouli. "Seismic Performance of Cantilever Retaining Walls with Clayey Backfills." In IFCEE 2015. Reston, VA: American Society of Civil Engineers, 2015. http://dx.doi.org/10.1061/9780784479087.130.

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Reports on the topic "Backfills"

1

Balsley, S. D., P. V. Brady, J. L. Krumhansl, and H. L. Anderson. {sup 129}I{sup -} and {sup 99}TcO{sub 4}-scavengers for low level radioactive waste backfills. Office of Scientific and Technical Information (OSTI), March 1997. http://dx.doi.org/10.2172/475667.

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P. Mariner. SEEPAGE/BACKFILL INTERACTIONS. Office of Scientific and Technical Information (OSTI), April 2000. http://dx.doi.org/10.2172/861905.

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Keller, R. L. Backfill Emplacement Analysis. Office of Scientific and Technical Information (OSTI), January 1997. http://dx.doi.org/10.2172/763120.

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Aston, T. R. C., and A. Annor. Catalogue of backfill literature. Natural Resources Canada/CMSS/Information Management, 1991. http://dx.doi.org/10.4095/328738.

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Mejias-Santiago, Mariely, Lyan I. Garcia, and Lulu Edwards. Rapid Airfield Damage Recovery Next Generation Backfill Technologies Comparison Experiment : Technology Comparison Experiment. Engineer Research and Development Center (U.S.), February 2021. http://dx.doi.org/10.21079/11681/39661.

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The Rapid Airfield Damage Recovery (RADR) Next Generation Backfill Technology Comparison Experiment was conducted in July 2017 at the East Campus of the U.S. Army Engineer Research and Development Center (ERDC), located in Vicksburg, MS. The experiment evaluated three different crater backfill technologies to compare their performance and develop a technology trade-off a nalysis. The RADR next generation backfill technologies were compared to the current RADR standard backfill method of flowable fill. Results from this experiment provided useful information on technology rankings and trade-offs. This effort resulted in successful crater backfill solutions that were recommended for further end user evaluation.
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Conca, J. Preparation for YMP backfill activities. Office of Scientific and Technical Information (OSTI), December 1998. http://dx.doi.org/10.2172/758822.

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Udd, J. E. Backfill research in Canadian mines. Natural Resources Canada/CMSS/Information Management, 1989. http://dx.doi.org/10.4095/325861.

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Kramer, N. E. Backfill LA Reference Design Feature Evaluation. Office of Scientific and Technical Information (OSTI), November 1999. http://dx.doi.org/10.2172/762896.

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Buscheck, T., K. Knauss, N. Rosenberg, and B. Viani. Geochemical alteration of backfill FY98 status report. Office of Scientific and Technical Information (OSTI), September 1998. http://dx.doi.org/10.2172/3020.

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R. Garrett. CLASSIFICATION OF THE MGR BACKFILL EMPLACEMENT SYSTEM. Office of Scientific and Technical Information (OSTI), August 1999. http://dx.doi.org/10.2172/860601.

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