Interaction mechanism of the interface between a deep buried sand and a paleo-weathered rock mass using a high normal stress direct shear apparatus

2015 ◽  
Vol 25 (4) ◽  
pp. 623-628
Author(s):  
Hanying Bai ◽  
Wenping Li ◽  
Qingfeng Ding ◽  
Qiqing Wang ◽  
Dongdong Yang
Keyword(s):  
Rock Mass ◽  
Normal Stress ◽  
Interaction Mechanism ◽  
Direct Shear ◽  
Weathered Rock ◽  
High Normal Stress ◽  
Direct Shear Apparatus

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.

Experimental Study on Shear Mechanical Characteristics of Cohesionless Granular Material

2011 ◽  
Vol 90-93 ◽  
pp. 230-233
Author(s):  
Hong Chun Xia ◽  
Guo Qing Zhou ◽  
Ze Chao Du
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Mechanical Characteristics ◽  
Stress Condition ◽  
Fine Sand ◽  
Shear Displacement ◽  
Direct Shear ◽  
Steel Particle ◽  
High Normal Stress ◽  
Fine Gravel

The direct shear mechanical characteristics of gravel, sand and steel particle were studied systematically using DRS-1 high normal stress direct and residual shear apparatus. The results show that the shear mechanical characteristics of gravel, sand and steel particle is different under different normal stress condition. For steel particle, the curves of shear stress-shear displacement present strain softening regardless of the magnitude of normal stress, and the shear displacement corresponding to the peak shear stress increases with the normal stress. Under low normal stress condition, the volume of fine gravel and steel particle expand, but the fine sand contracts at the beginning of direct shear and then contracts. Under high normal stress condition, the volume of steel particle contracts at the beginning of the direct shear and then contracts, but the fine sand and fine gravel contract throughout the direct shear. The particle breakage has significant effect on the shear strength of fine sand and fine gravel. Under the same high normal stress condition, the volume of fine gravel is greater than that of fine sand, which indicates that the fine gravel is easier to be crushed than the fine sand.

Development and Application of an Integrative Direct Shear Apparatus for Multi-scale Rock Mass Discontinuity

2013 ◽  
Vol 13 (9) ◽  
pp. 1558-1563
Author(s):  
L.V. Yuan-jun ◽  
D.U. Shi-gui ◽  
L.U.O. Zhan-you ◽  
H.U.A.N.G. Man
Keyword(s):  
Rock Mass ◽  
Direct Shear ◽  
Multi Scale ◽  
Direct Shear Apparatus

Influence of Dilation on the Axial Load of Bolt as Joint Subjected to Shearing

2013 ◽  
Vol 405-408 ◽  
pp. 326-330
Author(s):  
Wen Qiang Chen ◽  
Zhi Xin Jia ◽  
Yu Fei Zhao ◽  
Ji Jun Zhou ◽  
Xing Chao Lin
Keyword(s):  
Rock Mass ◽  
Normal Stress ◽  
Axial Load ◽  
Direct Shear Test ◽  
Shear Test ◽  
Load Transfer ◽  
Failure Zone ◽  
Direct Shear ◽  
Load Transfer Mechanism ◽  
The Relationship

Based on the load transfer mechanism of bolts, the relationship between the axial load and shear displacement of bolt changing with the dilatancy of joint was analyzed, then the theoretical solutions of axial load of the bolt were verified by the direct shear test of bolted rock mass with different normal stress (0.5MPa, 0.7MPa, 1.0MPa) applied on the joint. The results show that the calculated values fit well with the results of tests; the increment of dilation angle can enhance the axial force of bolt quickly, but decrease the length of crushing failure zone.

scholarly journals Strength Characteristics of Nonpenetrating Joint Rock Mass under Different Shear Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qingzhi Chen ◽  
Yuanming Liu ◽  
Shaoyun Pu
Keyword(s):  
Rock Mass ◽  
Normal Stress ◽  
Direct Shear Test ◽  
Shear Test ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Strength Characteristics ◽  
Triaxial Tests ◽  
Direct Shear ◽  
Rock Specimens

The mechanical property of jointed rock mass is an important factor to be considered in the analysis, evaluation, and design of actual rock engineering. The existence of joints threatens the stability and safety of underground engineering projects built in the rock mass. In order to study the change of mechanical properties and strength characteristics of nonpenetrating jointed rock mass under different test conditions, direct shear tests and triaxial tests were carried out. Direct shear tests under different normal stresses were carried out for nonpenetrating jointed rock mass to prepare specimens for triaxial tests. Then, triaxial tests were carried out to study the change of mechanical properties and strength characteristics of the nonpenetrating jointed rock mass. In the direct shear test part, the greater the normal stress is, the stronger the shear strength and the more serious the shear failure would be. The main conclusions are as follows: (1) the strength of rock mass would increase with the increase of confining pressure for those rock specimens with same degrees of shear after the direct shear test; (2) for rock specimens with different degrees of shear after the direct shear test, if the shearing degree of the rock specimen was greater, the strength of the rock specimen would be lower in the triaxial test; (3) for rock specimens with the same damage degree after direct shear test, the greater the normal stress in direct shear test is, the smaller the peak axial pressure would be in the triaxial test; (4) if the specimen was sheared under higher normal stress in direct shear test, the cohesion of it would be lower and the internal friction angle would be larger. For the specimens under the same normal stress, if the shear failure of one specimen was more serious, the cohesion of it would be smaller and the internal friction angle would be larger.

Experimental Study on Shear Mechanical Characteristics of Soil-Structure Interface under Different Normal Stress

2011 ◽  
Vol 243-249 ◽  
pp. 2332-2337 ◽  
Author(s):  
Hong Chun Xia ◽  
Guo Qing Zhou ◽  
Ze Chao Du
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Normal Stress ◽  
Soil Structure ◽  
Mechanical Characteristics ◽  
Shear Displacement ◽  
Interface Roughness ◽  
Displacement Curve ◽  
Direct Shear ◽  
High Normal Stress

The direct shear mechanical characteristics of soil-structure interface under different experimental condition were studied systematically using the DRS-1 high normal stress direct and residual shear apparatus. The results show that the normal stress is an important factor which determines the mechanical characteristics of soil-structure interface. The curve of shear stress-shear displacement presents strain softening when the normal stress<3MPa, linear hardening when =3~5MPa and strain hardening when12MPa, separately. At the same time, the volume of the soil expands when <3MPa and contracts when >3MPa. But the volume of the soil expands and contracts simultaneously during the process of direct shear when =3MPa.The roughness of the interface influences not only the shape of the shear stress-shear displacement curve but also the shear strength of the interface. Under same normal stress condition，the shear strength of interface increases with the roughness but the influence degree of interface roughness reduces gradually with the increase of normal stress. The grain breakage degree is different under different normal stress. It increases evidently with the increase of normal stress.

A New Direct Shear Apparatus for Rock Joints Specialized in Cyclic Loading

2021 ◽  
Author(s):  
Zhen Cui ◽  
Qian Sheng ◽  
Mao-chu Zhang ◽  
Jun-feng Cao ◽  
Xian-cheng Mei ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Rock Joints ◽  
Direct Shear ◽  
Direct Shear Apparatus

scholarly journals Evolution of Friction and Permeability in a Propped Fracture under Shear

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Fengshou Zhang ◽  
Yi Fang ◽  
Derek Elsworth ◽  
Chaoyi Wang ◽  
Xiaofeng Yang
Keyword(s):  
Normal Stress ◽  
Shear Loading ◽  
Particle Crushing ◽  
Normal Loading ◽  
Fracture Surfaces ◽  
Frictional Strength ◽  
Transport Response ◽  
Shear Slip ◽  
High Normal Stress ◽  
Proppant Embedment

We explore the evolution of friction and permeability of a propped fracture under shear. We examine the effects of normal stress, proppant thickness, proppant size, and fracture wall texture on the frictional and transport response of proppant packs confined between planar fracture surfaces. The proppant-absent and proppant-filled fractures show different frictional strength. For fractures with proppants, the frictional response is mainly controlled by the normal stress and proppant thickness. The depth of shearing-concurrent striations on fracture surfaces suggests that the magnitude of proppant embedment is controlled by the applied normal stress. Under high normal stress, the reduced friction implies that shear slip is more likely to occur on propped fractures in deeper reservoirs. The increase in the number of proppant layers, from monolayer to triple layers, significantly increases the friction of the propped fracture due to the interlocking of the particles and jamming. Permeability of the propped fracture is mainly controlled by the magnitude of the normal stress, the proppant thickness, and the proppant grain size. Permeability of the propped fracture decreases during shearing due to proppant particle crushing and related clogging. Proppants are prone to crushing if the shear loading evolves concurrently with the normal loading.

Shear strength and dilative characteristics of an unsaturated compacted completely decomposed granite soil

2010 ◽  
Vol 47 (10) ◽  
pp. 1112-1126 ◽  
Author(s):  
Md. Akhtar Hossain ◽  
Jian-Hua Yin
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Matric Suction ◽  
Water Retention Curve ◽  
Direct Shear ◽  
Normal Stresses ◽  
Soil Water Retention Curve ◽  
Strength Data ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Shear strength and dilative characteristics of a re-compacted completely decomposed granite (CDG) soil are studied by performing a series of single-stage consolidated drained direct shear tests under different matric suctions and net normal stresses. The axis-translation technique is applied to control the pore-water and pore-air pressures. A soil-water retention curve (SWRC) is obtained for the CDG soil from the equilibrium water content corresponding to each applied matric suction value for zero net normal stress using a modified direct shear apparatus. Shear strength increases with matric suction and net normal stress, and the failure envelope is observed to be linear. The apparent angle of internal friction and cohesion intercept increase with matric suction. A greater dilation angle is found at higher suctions with lower net normal stresses, while lower or zero dilation angles are observed under higher net normal stresses with lower suctions, also at a saturated condition. Experimental shear strength data are compared with the analytical shear strength results obtained from a previously modified model considering the SWRC, effective shear strength parameters, and analytical dilation angles. The experimental shear strength data are slightly higher than the analytical results under higher net normal stresses in a higher suction range.

Sign in / Sign up

Export Citation Format

Share Document