Dissertations / Theses on the topic 'Interface direct shear'

Esta tese apresenta os princípios e a formulação de um modelo não-linear de atrito estático em interface de concreto areia. A hipótese básica para desenvolvimento das equações consiste na ocorrência do atrito de deslizamento (atrito verdadeiro), do atrito de rolamento (rearranjo das partículas) e da dilatância (variação de volume durante o cisalhamento). A solução analítica do modelo considera o efeito da rugosidade da superfície de contato, da curva granulométrica da areia e do seu estado de compacidade inicial. Foram realizados ensaios de cisalhamento direto com carga normal constante em interface de contato entre concreto e areia com seção de 500 mm x 500 mm com o objetivo de permitir a calibração do modelo proposto. É discutida e sugerida a incorporação da equação constitutiva desse modelo em análises de interação solo-estrutura via método dos elementos finitos. Sua aplicabilidade é demonstrada através da análise 1D e 2D de estacas de atrito executadas em areia e submetidas a carregamentos de compressão<br>This thesis presents the principles and formulation underlying a concrete-sand interface nonlinear static friction model. The basic hypothesis employed in the development of the model equation takes into account the interface sliding friction (true friction), a rolling friction (particle rearrangement) and dilatancy(volume variation during shear). The model analytical solution considers the effect of roughness of the contact surface, the grain size distribution and its initial state of compactness of the sand. To calibrate the proposed model, a direct shear stress test under constant load was carried out along a 500mm x 500mm section concrete-sand interface. Furthermore, a discussion and suggestion of the inclusion of the model constitutive equation applied to the analysis of soil-structure interaction using the finite element method are presented. The applicability of the proposed model is proven through the analysis of 1-D and 2-D skin friction piles made of sand mass subjected to compression load

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>A aplicação de geossintéticos em obras geotécnicas vem crescendo intensamente nos últimos tempos, tornando cada vez mais importantes e necessários os estudos da resistência de interface para aplicação em projetos e obras. Em particular, tais estudos devem tratar das técnicas de ensaios de campo e de laboratório para a obtenção dos parâmetros de resistência (adesão e ângulo de atrito). Os ensaios de laboratório são utilizados com maior freqüência por serem mais acessíveis e de fácil execução. Os ensaios de campo reproduzem mais diretamente as condições das obras, mas apresentam como desvantagem o custo elevado e a dificuldade de execução. Este trabalho tem como finalidades apresentar o equipamento de ensaio utilizado e analisar os resultados de um programa em interfaces solo- geossintético. O programa experimental envolveu ensaios de rampa, cisalhamento direto convencional e cisalhamento direto inclinado em solo com granulação grosseira (brita), em contacto com as geomembranas e as geogrelhas. Os resultados foram analisados avaliando-se as influências da tensão confinante e da inserção dos geossintéticos, e comparandose os diferentes tipos de materiais e de técnicas de ensaio. A influência da tensão confinante foi estudada com base em três tensões confinantes distintas, de baixa magnitude (1,0; 1,7 e 2,4kPa). O aumento da tensão confinante implicou em um aumento, tanto do deslocamento até a ruptura quanto da resistência da interface. Este comportamento deve-se à possibilidade de rearranjo e imbricamento entre os grãos da brita. Em relação ao tipo de geossintético, a interface brita-geogrelha apresentou maior resistência do que a interface brita-geomembrana. Isto pode ser explicado em função da estrutura do geossintético, pois a geomembrana perde possui uma superfície lisa, o que favorece o deslizamento, ao contrário da geogrelha, que conta com o efeito do imbricamento do solo nas aberturas da malha.<br>The use of geosynthetics in geotechnical construction is growing up intensively on the last years, which make the study on interface strength more important and necessary to its application on projects and construction. Particularly, these studies should watch out field and laboratory tests in order to obtain strength parameters (adhesion and friction angle). Laboratory tests are more frequently used, due to their accessibility and easy execution. Field tests reproduce construction condition in a directly way, but have as disadvantages high cost and hard execution condition. The current research have as objectives present the test equipment used and analyze software results obtained for soil and geosynthetic interfaces. The experimental program involved ramp tests, conventional direct shear test and inclined direct shear test. This program was carried out on gravel soil in contact with two different types of geosynthetics (geomembrane and geogrids). Results were analyzed based on the influence of confining pressure and the introduction of geosynthetics, and comparing the different materials and test techniques. The confining pressure influence/importance was studied based on three different low magnitude confining pressures (1,0; 1,7 e 2,4kPa). The confining pressure increases resulted in an increase of both displacements until the failure and interface strength. This behavior could be explained due to the possibility of interlocking e between the gravel grains. Considering the geosynthetic type, gravel-geogrid interface presented higher strength than gravel- geomembrane interface. This could be explained by the structure of the geosynthetic; geomembrane has low strength due to its smooth surface, which benefits the slide. Geogrid instead, counts with the soil interlocking; effects in the mesh holes.

On présente tout d'abord une série d'essais de cisaillement direct 2D monotones et cycliques sur l'interface sable de Fontainebleau-plaque rugueuse et lisse, 'a contrainte normale constante (CNL) et à rigidité normale imposée (CNS). Le but de ces essais est de simuler la situation mécanique le long de pieux soumis à un grand nombre de cycles d'origine environnementale ou anthropique. Ces cycles (typiquement 10000) de faible amplitude (10'a 40 kPa en terme de contrainte de cisaillement) ne sont pas cens'es produire de rupture prématurée. Ces tests incluent une série de cycles d'amplitudes (successives) variées. Le problème de la perte de sable entre la boite et la plaque est trait'e avec attention. Nous avons interprété l'effet de la position du "centre des cycles" dans le plan de contraintes (variables cycliques moyennes) et de la densité initiale. Plusieurs facteurs tels que l'indice initial de densité (ID0), la contrainte normale cyclique moyenne (_n cm0), le niveau initial moyen de contrainte de cisaillement (_cm0), l'amplitude cyclique réduite (__) et la rigidité normale imposée (k qui dans cette thèse, va de 1000 'a 5000 kPa/mm), influencent les déplacements relatifs cycliques moyens normal ([u]cm) et tangentiel [w]cm) et sont pris en considération.On observe soit de la dilatance, soit de la contractance en accord avec l'état caractéristique développé par Luong. L'influence du chemin de contrainte (CNL ou CNS) est également analysée. Un modèle phénoménologique et analytique de comportement d'interface sur chemins cycliques CNL est propos'e. C'est également le cas pour le comportement monotone sur chemins oedométrique et CNL, la variable de mémoire unique étant la densité d'interface (sous contrainte) ou le déplacement relatif normal. Cette formulation permet de traiter, par incréments analytiques finis, les chemins comportant une variation d'amplitude cyclique, et les chemins CNS, ce qui introduit la notion de nombre de cycles équivalent. On notera que les chemins CNS sont toujours contractants. Ces essais sont utilisés pour aborder la simulation par éléments finis, avec le logiciel Plaxis, selon une approche de pseudo-viscoplasticité, le nombre de cycles tenant lieu de temps fictif. L'essai de cisaillement monotone'a la boite est modélisé en densités faible et forte, ainsi que deux essais de pieux modèles centrifugés, l'un en traction, l'autre en compression. Des recommandations sont proposées pour le calcul courant des pieux sous sollicitations cycliques. Cette thèse a été soutenue par l'ANR SOLCYP et le programme national " recherches sur le comportement des pieux soumis à des sollicitations cycliques".

This thesis describes a new macro-scale test device for assessing the large-displacement soil/solid interface shear strength at very low effective normal stresses (3 kPa to 6 kPa). The testing method arises from a need to obtain the interface friction between soils and epoxy-coated pipes under low effective normal stress levels which is an important consideration in the design of partly buried seabed pipelines. The test device is fundamentally similar to the conventional small-scale direct-shear apparatus except for its large footprint that provides a plan interface shear area of 1.72 m by 1.75 m. The device is designed to impart displacement-controlled interface-shearing at displacement rates ranging from 0.0001 mm/s to 1 mm/s and with the ability to reach a maximum interface shear displacement of 1.2 m. The desired normal stress at the soil/solid interface is obtained using surcharge loads externally applied by means of bulk sand or water masses, or both in certain cases. The device is instrumented with pressure transducers mounted flush with the top surface of the solid test surface for the measurement of pore water pressure at the shear interface, in turn, allowing accurate determination of the effective normal stress at the soil/solid interface during shearing. The key features of this device are described, and the device capabilities are demonstrated by testing three soil types (Fraser-River sand, non-plastic silt, kaolinite) on two test surfaces (mild steel, epoxy-coated mild steel) at effective normal stresses between 3 kPa and 7 kPa. Comparison of the test results with available findings from other devices is used to further confirm the suitability of the device for the intended purpose.

Le collage par adhérence moléculaire est un collage basé sur la mise en contact de deux surfaces sans l'utilisation de colle ou matériaux additionnels. Ce procédé de collage est utilisé dans de nombreuses applications, notamment dans les domaines de l'optique terrestre et spatiale. Bien qu'un prototype ait déjà passé avec succès l'environnement spatial - où les contraintes d'utilisations sont différentes de celles rencontrées sur Terre - la spatialisation de cette technologie nécessite une caractérisation plus fine du procédé ainsi qu'une amélioration de la tenue mécanique des interfaces adhérées afin de valider les normes de l'Agence spatiale Européenne. Pour répondre à cette problématique de spatialisation de la technologie, des essais mécaniques ainsi que des analyses chimiques ont été réalisés dans le but d'étudier l'influence de certains paramètres du procédé ) sur la tenue mécanique et l'énergie de collage. Ces essais ont également été réalisés afin de comparer les deux matériaux étudiés : le verre de silice et le Zérodur vis-à-vis de l'adhésion. A l'issue de ces essais, les paramètres à appliquer permettant de doubler la tenue mécanique des interfaces adhérées ont été déterminés. Parallèlement, une loi phénoménologique reliant l'énergie de collage aux précédents paramètres du procédé a été développée ainsi qu'un modèle macroscopique visant à décrire l'intensité d'adhésion. Ces deux modèles une fois couplés permettent de modéliser le comportement normal de l'interface en fonction des paramètres du procédé. Enfin, ces deux lois sont implémentées dans un code éléments finis afin de simuler la propagation de la fissure lors de l'essai de clivage au coin<br>Direct bonding consists in joining two surfaces without the use of any adhesive or additional material. This process is used in several applications, particularly in terrestrial and spatial optics. Although a prototype passed with success spatial environment - where constraints involved are very different from those encountered on Earth - this technology requires a more detailed characterization and an improvement of the mechanical strength of bonded interfaces in order to validate the European Space Agency standards. To address this issue, mechanical tests (double shear tests, cleavage tests and wedge tests) and chemical analysis (wetting tests and XPS spectroscopy) were performed in order to study the influence of some process parameters (roughness, relative air humidity during room temperature bonding, the annealing temperature and time) on the mechanical strength and the bonding energy. These tests compared the two materials used: fused silica glass and Zerodur glass. As a result of these tests, optimal parameters doubling the mechanical strength were also obtained. In the same time, a phenomenological law relating the bonding energy to the previous parameters is developed as well as a macroscopic model to describe the adhesion intensity. Both models when coupled describe the normal behavior of the bonded interface depending on the process parameters. Then, the both laws are implemented in a finite elements model in order to simulate the crack propagation during the wedge test

Le stockage de chaleur dans des géostructures énergétiques telles que des remblais est réalisable en installant des échangeurs horizontaux au sein des différentes couches de sol compacté. Dans ce système, l'énergie thermique qui est injectée en été via un fluide caloporteur circulant dans les échangeurs de chaleur, peut être extraite en période hivernale. Dans ces conditions, lors de la mise en service, le sol compacté est soumis à des variations de température quotidiennes et saisonnières. Ces variations pourraient modifier les performances thermo-hydro-mécaniques du sol compacté. Ainsi, le but de cette étude est d'étudier les performances thermiques et mécaniques d'un sol compacté lorsqu'il est soumis à des variations de température monotones et cycliques. Le sol étudié est un limon fréquemment utilisé dans les constructions de remblais en France. Le comportement thermique et mécanique du sol est étudié à un état de compactage correspondant aux propriétés thermiques optimales. Dans cet état, le sol compacté est non saturé ce qui complexifie l'estimation de ses propriétés thermiques. Pour pallier à ces difficultés, dans cette étude, un modèle inverse est proposé pour estimer les propriétés thermiques du sol compacté. L’efficacité du modèle est testée sur un jeu de données acquises dans la gamme de 20 à 50 °C dans un modèle réduit en laboratoire. Les valeurs obtenues sont ensuite comparées à des mesures classiques en laboratoire (méthodes en régime transitoire et en régime permanent). Cette méthode pourrait permettre de suivre l’évolution des propriétés thermiques du stockage et ainsi assurer son efficacité tout au long de sa durée de vie. La question de la stabilité à long terme de ces structures soumises à des variations thermiques monotones (5, 20 et 50 °C) et cycliques (5 à 50 °C) est ensuite abordée à l'aide d'essais oedomètriques et d’essais de cisaillement direct à température contrôlée. Les résultats des essais de compressibilité ont montré que l'effet de la variation de température est plus prononcé sous une contrainte verticale supérieure à la pression de préconsolidation. Les indices de compression et de gonflement peuvent être considérés comme indépendants des variations de température. Donc le tassement global du remblai dû aux variations thermiques pourrait être considéré comme négligeable. Les résultats des essais de cisaillement direct ont montré que les variations de température (monotones ou cycliques) augmentent la cohésion ce qui est avantageux pour la capacité portante et la stabilité des pentes des remblais. Dans la phase de conception d'un remblai de stockage, ces résultats seraient utiles au dimensionnement du système si des trajectoires thermomécaniques similaires à celles de cette étude sont respectées. Dans une dernière partie, une simulation numérique prenant en compte l'interaction sol-atmosphère est réalisée afin d’évaluer la performance thermique de ce sol compacté en conditions naturelles. Différentes profondeurs d'installation de boucles d'échangeurs de chaleur sont testéss ainsi que différents scénarios de stockage. Les résultats ont montré que le sol compacté augmente de 8.5% les performances du système par rapport à l'installation d'une boucle horizontale dans le sol naturel (non compacté). Les résultats de deux scénarios différents ont montré qu’en été avec un fluide ayant une température d'entrée de 50 °C augmente significativement la performance du système. De plus, une installation plus profonde des boucles horizontales améliore également la performance du système. Il convient de noter que le remblai est en interaction avec l'atmosphère depuis ses surfaces supérieure et latérale, l'efficacité thermique de la structure pourrait être affectée en raison des pertes de chaleur. Par conséquent, il est préférable de placer les échangeurs de chaleur loin des surfaces supérieures et latérales<br>Nowadays, thermal energy storage in geostructures like embankments can be possible by installing the horizontal heat exchangers in different layers of compacted soil. In this system, the thermal energy is stored in summer via a fluid, circulating in the heat exchangers, to be extracted in the demand period. When the serviceability of embankment as a medium to store the thermal energy starts, the compacted soil will be subjected to the daily and seasonally temperature variations. These seasonal temperature variations could modify the thermo-hydro-mechanical performance of the compacted soil. Thus, the aim of this study is to investigate the thermal and mechanical performances of a compacted soil when it is subjected to monotonic and cyclic temperature variations. The studied soil is a sandy lean clay that is frequently used in embankment constructions in France. The thermal and mechanical behavior of the soil are investigated at a compaction state corresponding to the optimal thermal properties. However, this compacted soil is unsaturated and the estimation of its thermal properties is complex. In this study, an inverse analytical model is proposed to estimate the thermal properties of the soil using temperature monitoring in the range of 20 to 50 °C in a soil compacted in a large container. The estimated thermal parameters were compared to classical laboratory measurements (transient and steady-state methods). The comparison showed that the estimated values were close to the results obtained in transient laboratory method. Using this method, the thermal efficiency of the compacted soil can be verified in the lifetime of the storage system. To ensure the structure stability, long-term mechanical response of these systems subjected to monotonic and cyclic temperature variations should be investigated. To achieve this aim, using temperature-controlled oedometric and direct shear devices, consolidation and shear parameters of the studied soil at different monotonic (5, 20, and 50 °C) and cyclic (5 to 50 °C) temperatures were investigated. The results of temperature-controlled oedometric tests showed that the effect of the temperature variation is more pronounced under vertical pressures higher than the preconsolidation pressure. The compression and swelling indexes could be considered independent of temperature variations. Therefore, the overall settlement of the embankment due to thermal variation near the heat exchangers could be considered negligible. The results of temperature-controlled direct shear tests showed that the temperature variations (monotonic heating or cooling, or temperature cycles) increased the cohesion which is beneficial for the bearing capacity and slope stability of embankments. These results can be directly used in the design of embankments to store thermal energy exposed to similar thermo-mechanical paths. Finally, the thermal performance of the compacted soil is verified using a numerical simulation considering the soil atmosphere interaction. Different depths installation of heat exchanger loops and different heat storage scenarios were simulated. The results showed that the compacted soil increases 8.5% the systems performance compared to the horizontal loop installation in the local soil. The results of two different scenarios show that an inlet fluid temperature of 50 °C in summer increases highly the system performance (13.7% to 41.4%) while the improvement is less significant (0% to 4.8%) for the ambient inlet temperature. Moreover, a deeper installation of horizontal loops increases the system performance. From the numerical simulation results can be concealed that the embankment is in interaction with the atmosphere from its upper and lateral surfaces, the thermal efficiency of the structure could be affected due to heat losses. Therefore, it is preferable to place the heat exchangers away from the top and side surfaces

Thesis (M.S.)--University of Wisconsin--Madison, 1999.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 92-94).

碩士<br>國立暨南國際大學<br>地震與防災工程研究所<br>97<br>The interface friction coefficient between different soils and geosynthetics by obtaining from large-scale direct shear test has been widely used in designing of reinforced earth structure. Most of the direct shear tests are usually performed the geogrid and same soil at upper and lower layer of shear box. The lack of research by using direct shear test to observe the shear band of soil particles. Therefore this study adopt a transparent large-scale direct shear box with five opening size of grid and four different soil particle size to observe the flow characeteristics of soil particle at interface shear band by using a digital camera. Recording interface friction changes and analyize the change of different geogrid characteristics and between soil particles. The testing results show gravel particles and geogrid have good interaction behavior. Failure surface of shear band will be far away from the location of geogrid and interface area. The bandwidth is about (9.2mm-26mm)、(8.7mm-13.4mm) that is measured at Vietnam sand. The interface shear band bandwidth is about (4mm-6mm) at Ottawa sand and gravel. Observation of Ottawa sand interface shear band bandwidth about (1.2mm-2.6mm),effect of sand particle size on the interface shear band with the scope of the smallest. The result of interface shear observation use four different soil particle size and five different kinds of type geogrid of the above mentioned, the interface shear band ranked in descending order are as follows: gravel＞Vietnam sand＞Ottawa sand. Understandably, the different soil particle size can show the different interface behavior, despite in reinforced soil condition or in unreinforced soil condition, gravel specimen has more visible shear band than Vietnam sand and Ottawa sand. Under the same conditions, the gravel has the higher shear strength more than Vietnam sand and standard sand, soil dilation behavior also more pronounced. This study is to explore Interface shear observation and to understand the soil in the geogrid rib development, in this test can found that geogrid surface and geogrid rib tensile strength with soil particle mobile has the quite Obviously influence.

碩士<br>國立中興大學<br>土木工程學系所<br>102<br>No-dig methods such as pipe-jacking and shielded TBMs are popularly used in public utilities. Because of the advantage of cost, pipe-jacking is more popular than shielded TBMs. However, how to predict jacking force in different geological conditions, and choose proper tunneling machines, or estimate tool life and maintenance, will influence the cost of contract a lot. The jacking force applied by the jacking station has to exceed the penetration resistance at the cutting head of TBM and the total frictional resistance of the jacking machine and the pipe string. The amount of the penetration resistance in homogeneous ground conditions is nearly constant, the frictional resistance is increasing with increasing length. The purpose of this study is to use Torsional Shear Testing to estimate the frictional property of pipe-soil interface, then use the Direct Shear Testing Method to make the correlation between this testing methods. In this study, prepared the gravel formation sample with removing sample which grains size are more than 3/2". Then used standard proctor compaction method to make soil sample compact. With the condition of different interface, such as no lubricants, bentonite suspension, bentonite suspension with polymers, tried to estimate the frictional property of pipe-soil interface by Torsional Shear Testing and Direct Shear Testing Methods. For the injecting of lubricants in the annular gap, the annular gap may not fill with lubricants. This study tries to discuss the amount of jacking force, when the injecting of lubricants may not fill with the annular gap of jacking pipe .

碩士<br>國立暨南國際大學<br>土木工程學系<br>94<br>The reinforcing technique which has many advantages like high workability and low cost has been widely used in recent years.And the PET geogrid is the most prevailing reinforcing material in Taiwan nowadays. So far, HDPE or PP geogrid are often selected to discuss the interface friction angle in the large-scale direct shear test. However, the PET geogrid tests are relatively rare, so this study uses PET geogrids to test and discuss its interface friction properties. Because geogrid’s design applicability varies with field condition, this study uses large-scale direct shear test to discuss the interface friction properties between different factors of PET geogrids and three kinds of soil (Ottawa sand, gravel and laterite).Also, the relationship of gravel diameter and geogrid opening size, the influence of different lower shear box to test result, and whether the interaction between soil and geogrid using various lower box of the device exists or not are discussed in this article. From the test of Ottawa sand, the result shows that the geogrid's strength is not very influential to the test, but the opening size is. The smaller the geogrid’s opening size, the higher the interface friction angle. And the angle would be higher in sand/geogrid interface than in sand/sand one, however, it would be lower in gravel and laterite test.As to the relationship between gravel size and geogrid opening size, the test results show that if the ratio of particle size to opening size is greater than 20, the interlocking of particles would not be affected by the intervention of geogrid on interface. This study discuss if the interlocking exists in the soil of direct shear test, the result shows that under three different soil, the interlocking can be found, and the interface friction angle would be higher. This result demonstrates that the interlocking in the soil do exist in the direct shear test. When discussing the influence of different types of lower box to the test. The results show that soil disturbing would occur in the larger lower box, and the steel plate which replaces the lower box would lack interlocking mechanism. Thus the values from the test would be lower.

碩士<br>國立交通大學<br>土木工程系所<br>92<br>The Mechanical Behavior of Concrete-Poorly Cemented Sandstone Interface under Constant Normal Stiffness Direct Shear Test Student: Szu-Ting Wu Advisor： Dr. Jyh-Jong Liao Department of Civil Engineering National Chiao Tung University Abstract The mechanical properties of soft rock are distinct those of hard rock or soil, so the failure mechanism of soft rock slope may be different. The existing study of the pile behavior is based on the experience of pile foundation and the theory of soil mechanics with the safety factor according to the uniaxial compressive strength and the interface roughness；Therefore, for large scale constructions, it is required for the Pile-load test results to get the more reliable pile-rock interaction. To estimate the shear strength of the interface of rock and concrete, it is more appropriate to adopt the results of constant normal stiffness direct shear test and the stiffness between pile shaft and soft rock. Hence, Direct shear test under constant normal stiffness is valuable to perform on the interface of concrete-soft rock. This thesis aims to investigate the mechanical behavior of Concrete-Poorly Cemented Sandstone Interface by direct shear test under constant normal stiffness. The experimental results show that normal stiffness and initial normal stress strongly influence the behavior. However, the influence of roughness of interface can be neglected in this study. Keywords : soft rock, normal stiffness, direct shear, interface.

Documentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeiros<br>Usage of masonry materials in a country like Iran is still significantly high. As most of the failures during an earthquake in this system is failure caused by low ductility of cement mortars and also the high rate of carbon dioxide produced by cement. Experiences of Kermanshah earthquake in 2017 in Iran has doubled the importance of this issue. Hence, in the present investigation, an attempt to enhance the shear bond characteristics of structures constructed by masonry using green materials has been made. “Taftan” natural Pozzolan and two types of rice husk ash (RHA) was used in mix design of used mortars as a green material. In this investigation, a direct shear test (DST) device is modified and proposed to determine brick-mortar shear bond strength. The proposed method of applying DST has the advantageous of changing normal load and determine pure bond characteristics. For this purpose, two bricks bonded to each other by a mortar and subjected to the shear load. Tests were performed using DST for nine different types of mortars with different normal loads. The effect of increasing shear bond strength over time was also studied. Tests showed that using waste material like RHA in mortar is reasonable as its causes to the increase mortar plasticity and failure strain and also reduce the cost of mortar and its environmental effect.

Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials (No. 4 natural sand, No. 24 stone sand and No. 5, No. 8, No. 43 aggregates), were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table at the highest amplitude and frequency of vibration available in both equipment. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.