Effect of stress paths on the behaviour of sand–steel interfaces

1996 ◽  
Vol 33 (6) ◽  
pp. 853-865 ◽  
Author(s):  
Erman Evgin ◽  
Kazem Fakharian
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Three Dimensional ◽  
Soil Mass ◽  
Tangential Displacement ◽  
Residual Shear Strength ◽  
Normal Stiffness ◽  
Dense Sand ◽  
Stiffness Constant ◽  
Constant Normal Stiffness

An apparatus has been developed to carry out two- and three-dimensional tests on interfaces between soils and structural materials. The soil container facilitates both the sliding displacement at the interface and the shear deformation in the soil mass. The apparatus has the capability of maintaining the normal stiffness constant during shearing. In constant normal stiffness tests, the normal stress is adjusted continuously by a computer-controlled system to keep the normal stiffness at a desired value. In addition to constant normal stiffness tests, conventional types of tests can be performed during which the average normal stress acting on the interface is kept constant. In all types of three-dimensional tests, the interface can be subjected to tangential loading in two orhtogonal directions simultaneously. Experiments were conducted to study the two- and three-dimensional behaviour of an interface between a dense sand and a rough steel surface under both constant normal stress and constant normal stiffness conditions. The influence of various stress paths on the stress–displacement relations and shear strength characteristics of the interface are investigated. The experimental results indicate that the coefficients of friction corresponding to the resultant peak and residual shear strengths are independent of stress paths. The shear stress – tangential displacement and volume change behaviour of the interface, however, are significantly influenced by stress paths. Key words: interface testing, simple shear, peak and residual shear strength, three-dimensional, constant normal stiffness, stress path.

scholarly journals A shear strength model for idealised infilled joints under constant normal stiffness

Géotechnique ◽  
2005 ◽  
Vol 55 (3) ◽  
pp. 215-226 ◽  
Author(s):  
B. Indraratna ◽  
H. S. Welideniya ◽  
E. T. Brown
Keyword(s):  
Shear Strength ◽  
Strength Model ◽  
Normal Stiffness ◽  
Constant Normal Stiffness

scholarly journals Shear rate effect on the residual strength characteristics of saturated loess

2019 ◽  
Author(s):  
Baoqin Lian ◽  
Jianbing Peng ◽  
Qiangbing Huang
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Normal Stress ◽  
Rate Effect ◽  
Shear Tests ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
The Difference

Abstract. Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of ring shear tests were carried out on loess from three landslides at two shear rates (0.1 mm/min and 1 mm/min). Naturally drained ring shear tests results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase of shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than that under the higher normal stress. The tests results revealed that the difference in the residual friction angle фr at the two shear rates, фr (1)–фr (0.1), under each normal stress level were either positive or negative values. However, the difference фr(1)–фr (0.1) under all normal stresses was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in loess area. Such negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimen to restore broken bonds at low shear rates.

scholarly journals Experimental Study on Influence of Joint Surface Morphology on Strength and Deformation of Nonthrough Jointed Rock Masses under Direct Shear

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yuanming Liu ◽  
Qingzhi Chen ◽  
Huiyu Chen ◽  
Xun Ou ◽  
Dafu Wu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Normal Stress ◽  
Failure Mode ◽  
Jointed Rock ◽  
Tangential Displacement ◽  
Direct Shear ◽  
Jointed Rock Masses ◽  
Final Failure ◽  
Joint Morphology

Direct shear tests were carried out on nonthrough jointed rock masses (NTJRM) with three types of joints under five normal stresses. The strength characteristics of shear strength, initial crack strength, and residual strength and the deformation characteristics of tangential displacement and dilatancy displacement as well as the transformation of failure mode and the variation of shear parameters of rock mass with different joint morphology are studied. Under the same normal stress, with the increase of joint undulation, the shear strength of NTJRM increases, and the corresponding tangential displacement of NTJRM increases. Two typical failure modes are observed: TTTS mode and TSSS mode. TTTS model indicates that the initial failure, extension failure, and final failure of rock mass are caused by tensile action, while the failure mode of through plane is formed by shear action. The initial failure of TSSS mode rock mass is caused by tensile action, while the expansion and final failure are caused by shear action, and the failure mode of through plane is formed under shear action. When the joint undulation is small and the normal stress is small, NTJRM will fail in TTTS mode; when the joint undulation is large and the normal stress is large, NTJRM will fail in TSSS mode. The results show that the shear parameters of NTJRM are related to the joint morphology, the bond force increases with the increase of joint undulation, and the internal friction angle increases with the increase of joint undulation. The research results of direct shear test of nonthrough jointed rock mass can provide reference for related research.

scholarly journals Numerical Analysis Method of Shear Properties of Infilled Joints under Constant Normal Stiffness Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xiangyu Wang ◽  
Ruofan Wang ◽  
Zizheng Zhang
Keyword(s):  
Numerical Analysis ◽  
Normal Stress ◽  
Shear Failure ◽  
Rock Joints ◽  
Analysis Method ◽  
Shear Properties ◽  
Normal Stiffness ◽  
Numerical Analysis Method ◽  
Constant Normal Stiffness ◽  
Good Agreement

The direct shear test is implemented in this paper for infilled joints under constant normal stiffness (CNS) condition with the finite difference software FLAC3D. The CNS condition was performed based on a servoprogram developed by FISH language. The effects of initial normal stress, undulating angle, and infilled ratio on the shear failure mode of infilled joints under CNS are revealed based on numerical simulation. It is found that the shear strength of infilled joints will grow along with the increase of the undulating angle and the decrease of the infilled ratio. The numerical analysis method is also able to quantify the effect of multiple factors (initial normal stress and infilled ratio) on shear properties of infilled joints. The model shows a good agreement with the experimental results available in the literatures. Therefore, this study proposed and verified a numerical analysis method capable of studying the effects of normal stress, undulating angles, and infilled ratio on the shear behavior of infilled rock joints.

scholarly journals Three-dimensional monotonic and cyclic behavior of a gravel–steel interface from large-scale simple-shear tests

2018 ◽  
Vol 55 (11) ◽  
pp. 1657-1667 ◽  
Author(s):  
Da-kuo Feng ◽  
Jian-min Zhang ◽  
Li-jun Deng
Keyword(s):  
Normal Stress ◽  
Simple Shear ◽  
Large Scale ◽  
Three Dimensional ◽  
Vital Role ◽  
Cyclic Behavior ◽  
Normal Displacement ◽  
Tangential Displacement ◽  
Interface Thickness ◽  
Cyclic Shear

Gravel–structure interfaces are involved in many large-scale geotechnical applications and play a vital role in the performance of soil–structure interaction systems. A large-scale simple-shear device was professionally developed and used to investigate three-dimensional (3-D) monotonic and cyclic shear behavior of a gravel–steel interface in two-way beeline, cross, and circular shear paths. The soil deformation was measured and was used to determine the interface thickness. The deforming and sliding displacements of the interface were quantified and separated from the total tangential displacement. Results show that the interface thickness is about 6–7 times the mean grain size, D50, independent of the normal stress and shear path. Under 3-D loading conditions, the shear stress vs. tangential displacement hysteretic response exhibits notably 3-D features. The interface becomes stiffer because of the hardening behavior of the gravel during cyclic shearing. The total normal displacement can be divided into irreversible and reversible components, which present different responses. The peak shear strength is mobilized when the interface dilatancy rate reaches the maximum at a sliding displacement of about 0.5D50, and behaves in an anisotropic manner caused by the shear orientation effect. The normal stress and shear paths have significant influences on the 3-D interface behavior.

Shear coupling effect of monotonic and cyclic behavior of the interface between steel and gravel

2019 ◽  
Vol 56 (6) ◽  
pp. 876-884 ◽  
Author(s):  
Zia ur Rehman ◽  
Ga Zhang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Cyclic Behavior ◽  
Tangential Displacement ◽  
Orthogonal Direction ◽  
Gravelly Soil ◽  
Shear Coupling

Three-dimensional behavior of the interface between a structure and gravelly soil is of great concern in the design and construction of large-scale projects. A series of three-dimensional tests were conducted to investigate the effect of shear coupling on the monotonic and cyclic behavior of such an interface. In these tests, monotonic shear was applied to the interface first and then the monotonic and cyclic shears were applied in the orthogonal direction while the original shear was maintained. Based on the test observations, the shear strength of the interface was found to be independent of the shear coupling and proportional to the normal stress. Significant tangential displacement is induced by the orthogonal shear application and the deflection direction of the tangential displacement is proportional to the square of the ratio between the orthogonal shear stress and shear strength. The interface exhibits significant dilatancy due to a three-dimensional shear application, which is divided into reversible and irreversible components. Shear coupling remarkably affects the magnitude and transition shear stress of the reversible dilatancy component. There persists a significant aeolotropy of the interface evenly under the shear coupling condition. Particle crushing near the structure was observed to be enhanced due to the shear coupling.

scholarly journals Shear rate effect on the residual strength characteristics of saturated loess in naturally drained ring shear tests

2020 ◽  
Vol 20 (10) ◽  
pp. 2843-2856
Author(s):  
Baoqin Lian ◽  
Xingang Wang ◽  
Jianbing Peng ◽  
Qiangbing Huang
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Normal Stress ◽  
Rate Effect ◽  
Shear Tests ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
The Difference

Abstract. Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of naturally drained ring shear tests were carried out on loess from three landslides at two shear rates (0.1 and 1 mm min−1). Experimental results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase in shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than those under the higher normal stress. Moreover, specimens with almost the same low fraction of clay (CF) showed a similar shear rate effect on the residual friction coefficient, with normal stress increasing, whereas specimens with high CF (24 %) showed a contrasting tendency, indicating that such an effect is closely associated with CF. The test results revealed that the difference in the residual friction angle ϕr at the two shear rates, ϕr(1)−ϕr(0.1) under each normal stress level are either positive or negative values, of which the maximum magnitude is about 0.8∘. However, the difference ϕr(1)−ϕr(0.1) determined under all normal stress levels was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in the loess area. Such a negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimens to restore broken bonds at low shear rates.

scholarly journals Experimental Study on the Shear-Flow Coupled Behavior of Tension Fractures Under Constant Normal Stiffness Boundary Conditions

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 57 ◽  
Author(s):  
Changsheng Wang ◽  
Yujing Jiang ◽  
Hengjie Luan ◽  
Jiankang Liu ◽  
Satoshi Sugimoto
Keyword(s):  
Surface Roughness ◽  
Shear Stress ◽  
Shear Flow ◽  
Boundary Conditions ◽  
Normal Stress ◽  
Growth Stage ◽  
Normal Stiffness ◽  
Peak Shear Stress ◽  
Hydraulic Aperture ◽  
Constant Normal Stiffness

This study experimentally investigated the effects of fracture surface roughness, normal stiffness, and initial normal stress on the shear-flow behavior of rough-walled rock fractures. A series of shear-flow tests were performed on two rough fractures, under various constant normal stiffness (CNS) boundary conditions. The results showed that the CNS boundary conditions have a significant influence on the mechanical and hydraulic behaviors of fractures, during shearing. The peak shear stress shows an increasing trend with the increases in the initial normal stress and fracture roughness. The residual shear stress increases with increasing the surface roughness, normal stiffness, and initial normal stress. The dilation of fracture is restrained more significantly under high normal stiffness and initial normal stress conditions. The hydraulic tests show that the evolutions of transmissivity and hydraulic aperture exhibit a three-stage behavior, during the shear process—a slight decrease stage due to the shear contraction, a fast growth stage due to shear dilation, and a slow growth stage due to the reduction rate of the mechanical aperture increment. The transmissivity and hydraulic aperture decreased, gradually, as the normal stiffness and initial normal stress increase.

scholarly journals A shear strength model for idealised infilled joints under constant normal stiffness

Géotechnique ◽  
2005 ◽  
Vol 55 (3) ◽  
pp. 215-226 ◽  
Author(s):  
B. Indraratna ◽  
H. S. Welideniya ◽  
E. T. Brown
Keyword(s):  
Shear Strength ◽  
Strength Model ◽  
Normal Stiffness ◽  
Constant Normal Stiffness
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