Numerical Simulation for Shear Characteristics of Rock-Mass Structural Plane

2013 ◽  
Vol 734-737 ◽  
pp. 574-578
Author(s):  
Bao Yuan Yuan ◽  
Qi Wang ◽  
Hai Feng Lu
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Friction Angle ◽  
Normal Displacement ◽  
Displacement Curve ◽  
Peak Shear Strength ◽  
Structural Plane ◽  
Linear Feature ◽  
Stress And Deformation ◽  
The Stability

The characteristics of structural plane are very important to the stability of rock mass.In this paper,the stress and deformation characteristics of structural plane under direct shear conditions are analyzed based on FLAC3D code.And the influence of structural plane inhomogeneity to shear test was discussed.The results obtained in this paper indicate that, with the increase of normal stress, the shear strength of structural plane is constantly increasing,and the tow of them presents linear feature significantly. The normal displacement and shear displacement increase with the rise of the normal stress too. The peak shear strength increases gradually on the condition of uneven friction angle in the interface. This situation changes smaller when the discrete degree of friction angle is small. The peak shear strength increases significantly when the discrete degree of friction angle is big,and the stress-displacement curve exhibits a nonlinear characteristics before yield.

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

scholarly journals Water Softening Mechanism and Strength Model for Saturated Carbonaceous Mudstone in Panzhihua Airport, China

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ziwen Wang ◽  
Jifang Du ◽  
Shuaifeng Wu ◽  
Yingqi Wei ◽  
Jianzhang Xiao ◽  
...  
Keyword(s):  
Shear Strength ◽  
Water Saturation ◽  
Structural Characteristics ◽  
Water Immersion ◽  
Analytical Techniques ◽  
Friction Angle ◽  
Mechanical Tests ◽  
Water Softening ◽  
Softening Mechanism ◽  
The Stability

To identify the water softening mechanisms that caused landslides in Panzhihua Airport, China, property and saturation tests of the mudstones extracted from a representative landslide were proposed. In this paper, water saturation tests were carried out on samples of carbonaceous mudstone collected from the east side of the No. 12 landslide at the airport. A number of different analytical techniques and mechanical tests were used to determine changes in chemical composition, mineral assemblages, and mudstone structural characteristics, including shear strength, after the mudstone had been softened. Three kinds of changes caused by water and three mudstone softening stages are proposed. The results show that the water has a significant influence on the properties of the mudstone, so the stability of the mudstone in the watery period is a big threat to the upper structure. A model for water immersion mudstone strength softening is developed. The model incorporates a permeability coefficient, the hydraulic gradient, and time; the model can be used to determine the mudstone’s shear strength and internal friction angle. This study provides a reference for the study of rock softened by water immersion.

scholarly journals Large-Scale Direct Shear Test on Scrap Tire Strip Reinforced Brick Powder

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Qiang Ma ◽  
Qian Deng ◽  
Jia Mou ◽  
Shuo Yang ◽  
Xu Zhang
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Friction Angle ◽  
Vertical Displacement ◽  
Direct Shear ◽  
Peak Shear Strength ◽  
Scrap Tire ◽  
Volume Percentage ◽  
Optimal Dimension ◽  
Brick Powder

In order to clear the shear mechanism of the scrap tire strips reinforced brick powder, a series of large-scale direct shear tests were carried out on the pure brick powder and reinforced brick powder. The scrap tire strips with 50 mm in length, 5 mm in thickness, and 10 mm, 30 mm, and 50 mm in width were put into the brick powder with volume percentages of 2%, 6%, and 10% as reinforcement, respectively. The results show that the internal friction angle and cohesion increase by adding scrap tire strips into brick powder. The peak shear strength of reinforced brick powder initially decreases, thereafter increases and finally decreases with the increase of volume percentage of the scrap tire strips. And the peak shear strength increases in the initial stage and then decreases with the increase of the scrap tire strips dimension. The optimal dimension and volume percentage of the scrap tire strips are 50 mm × 30 mm × 5 mm and 6%, respectively. In addition, the scrap tire strips provide constraints to restrict the vertical displacement of integral reinforced brick powder, and relative to the pure brick powder, the larger the vertical load is, the greater the decrease of vertical displacement is.

scholarly journals Numerical Shear Tests on the Scale Effect of Rock Joints under CNL and CND Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xige Liu ◽  
Wancheng Zhu ◽  
Lankun Li
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Scale Effect ◽  
Shear Behavior ◽  
Shear Displacement ◽  
Rock Joints ◽  
Peak Shear Strength ◽  
Normal Stresses ◽  
Shear Tests ◽  
Joint Length

The scale effect of rock joint shear behavior is an important subject in the field of rock mechanics. There is yet a lack of consensus regarding whether the shear strength of rock joints increases, decreases, or remains unchanged as the joint size increases. To explore this issue, a series of repeated and enlarged numerical joint models were established in this study using the particle flow code (PFC2D). The microparameters were calibrated by uniaxial compression tests and shear tests on the concrete material under the constant normal loading (CNL) condition. Three different normal stresses were adopted in numerical shear tests with joint specimen lengths ranging from 100 mm to 800 mm. In addition to the commonly used CNL, the constant normal displacement (CND) condition was established for the purposes of this study; the CND can be considered an extreme case of the constant normal stiffness (CNS) condition. The shear stress-shear displacement curves changed from brittle failure to ductile failure alongside a gradual decrease in peak shear strength as joint length increased. That is, an overall negative scale effect was observed. Positive scale effect or no scale effect is also possible within a limited joint length range. A positive correlation was also observed between the peak shear displacement and joint length, and a negative correlation between shear stiffness and joint length. These above statements are applicable to both repeated and enlarged joints under either CNL or CND conditions. When the normal stress is sufficiently high and shear dilatancy displacement is very small, the shear behavior of rock joints under CNL and CND conditions seems to be consistent. However, for shear tests under low initial normal stress, the peak shear strength achieved under the CND condition is much higher than that under the CNL condition, as the normal stresses of enlarged joints increase to greater extent than the repeated ones during shearing.

Numerical Analysis of Deformation and Stability of Rock Slope under Rainfall Condition

2012 ◽  
Vol 594-597 ◽  
pp. 2506-2511
Author(s):  
Bing Hua Zhao ◽  
Shi Ping Zhang
Keyword(s):  
Rock Slope ◽  
Friction Angle ◽  
Element Model ◽  
Rainfall Condition ◽  
Deformation Law ◽  
Stability Of Slope ◽  
Stress And Deformation ◽  
Set Up ◽  
The Stability ◽  
Stability Of Rock Slope

Combining an example of rock slope engineering, the finite element model of excavation, reinforcement with rainfall infiltration conditions is built up. The process of stage excavation and reinforcement of the slope are simulated, and the stress and deformation law and displacement change of the slope during each stage period are analyzed, and the stability of slope is evaluated under some conditions. Moreover, the discontinuous deformatioanalysis model is set up, the limited internal friction angle of the sliding face of slope is obtained, and the slope stability is evaluated. It was shown that the conclusion of two methods was consistent, and the slope was basically stable.

Experimental Study on Shear Behavior of Short-Fill-Age MSW

2010 ◽  
Vol 113-116 ◽  
pp. 479-483
Author(s):  
Li Sha Ma ◽  
Huan Li Wang ◽  
Wei Wang ◽  
Zheng Wen Zhang
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Friction Angle ◽  
Exponential Model ◽  
Hyperbolic Model ◽  
Displacement Curve ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Cohesion Force ◽  
Coulomb Criterion

Mechanical behavior of municipal solid waste (MSW) is important to geo-environment engineering, and it is necessary to properly understand it. Laboratory direct shear tests were conducted on MSW with 3 short fill ages, namely 1d, 4d and 7d. Three different densities were taken into accounted in each fill age. Experimental data show that MSW’s shear failure still satisfies the Mohr-Coulomb criterion. As to bigger density, shear strength of MSW increases within 1-7d fill age. When density becomes smaller, its shear strength increases within 1-4d fill age but decreases within 4-7d fill age. With fill-age developing, friction angle of MSW increase monotonously, but cohesion force of it first increases and then decreases. Experimented shear stress-displacement curve of MSW can not be well fitted by either hyperbolic model or exponential model. This experimental research is helpful for design and numerical simulation of corresponding MSW landfill.

scholarly journals Strength Characteristics and Slope Stability of Expansive Soil from Pingdingshan, China

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ju-yun Zhai ◽  
Xiang-yong Cai
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Expansive Soil ◽  
Friction Angle ◽  
Natural Soil ◽  
Soil Slope ◽  
The Finite Element Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
The Stability

By analyzing the characteristics of expansive soil from Pingdingshan, China, the shear strength parameters at different water contents, dry densities, and dry-wet cycles of expansive soil are obtained. It is found that, at higher soil-water content, the internal friction angle is 0° and the shallow layer of expansive soil slope will collapse and destroy; this has nothing to do with the height of the slope and the size of the slope. The parameters of soil influenced by atmosphere are the ones which have gone through dry-wet cycles, and the parameters of soil without atmospheric influence are the same as those of natural soil. In the analysis of slope stability, the shear strength parameters of soil can be determined by using the finite element method, and the stability coefficient of the expansive soil slope can be calculated.

scholarly journals FRICTION ANGLE OF POLISHED SURFACES OF SANDSTONE AND CONGLOMERATE FROM THE SEMANGGOL FORMATION, BERIS DAM, KEDAH DARUL AMAN

2020 ◽  
Vol 4 (1) ◽  
pp. 09-12
Author(s):  
J. K. Raj
Keyword(s):  
Shear Strength ◽  
Laboratory Tests ◽  
Friction Angle ◽  
Normal Displacement ◽  
Test Conditions ◽  
Apparent Cohesion ◽  
Shear Box

The Beris Dam is founded on a sequence of thick bedded to massive conglomerate and gritstone with some sandstone and mudstone, mapped as the Semanggol Formation of Triassic age. Portable shear box tests on polished surfaces of a sandstone, and a conglomerate, core yield friction angles of 18.0o and 20.8o, respectively. These friction angles are comparable with residual friction angles of between 17.5o and 19.0o determined in field and laboratory tests on sheared mudstone surfaces of the Semanggol Formation at the Muda Dam. Apparent cohesion values determined in the portable shear box tests result from the restricted normal displacement test conditions and should not be considered in shear strength calculations.

scholarly journals Experimental Study on the Shearing Behaviour on the Interface between Coarse Sand and Concrete under High Stress

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Junkun Tan ◽  
Jiaqi Guo ◽  
Shifan Qiao ◽  
Changrui Dong ◽  
Ziyong Cai ◽  
...  
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Normal Stress ◽  
High Stress ◽  
Shear Stiffness ◽  
Coarse Sand ◽  
Shear Behaviour ◽  
Hyperbolic Model ◽  
Displacement Curve ◽  
Ultimate Shear Strength

The shear behaviour on the interface between soil and structure is a research hot point. Based on the RMT-150B rock mechanics test system, a series of high-stress direct tests were performed on the coarse sand under the condition of different moisture contents and concrete substrates with different rough and hardness. The results showed that the shear stress-displacement curve and volumetric strain-displacement curve of the interface under high stress could be fitted by a hyperbolic model; the ultimate shear strength and initial shear stiffness of the interface both increased with the normal stress while the shear stiffness decreased with the shear displacement. The crushing rate of the coarse sand particles on the interface increased with the normal stress. After the range analysis for the influencing factors of the interface’s shearing behaviour, it was shown that for the ultimate shear strength, their sequence of influencing degree was normal stress, the roughness of interface, moisture content, and hardness of concrete base; for the initial shear strength, the sequence was normal stress, moisture content, interface roughness, and basal hardness. As for dry sand, the possibility of relative particle crushing was higher than that of sand with a moisture content of 8%, and a peak of crushing occurred when the moisture content was 16%.

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