scholarly journals Embankment Displacement PLAXIS Simulation and Microstructural Behavior of Treated-Coal Gangue

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 218 ◽  
Author(s):  
Xiaoyun Yang ◽  
Yan Zhang ◽  
Zhuhan Li
Keyword(s):  
Shear Strength ◽  
Road Construction ◽  
Friction Angle ◽  
Coal Gangue ◽  
Filling Material ◽  
Carbon Structure ◽  
Microscopic Mechanism ◽  
Maximum Displacement ◽  
Microstructural Behavior ◽  
The Stability

The purpose of this study is to investigate the displacement of coal gangue filling material in road construction and microstructural behavior of treated coal gangue by considering the environmental factors of aqueous solutions with different acidity. The displacement analysis of the coal gangue embankment model has been done by means of the finite element method PLAXIS. Furthermore, using the scanning electron microscope, the energy dispersive system, and the Raman spectrometer to analyze the microscopic mechanism in the view of microstructure, elements, the integrity of carbon structure and the stability of chemical bonds of coal gangue. The results show that the larger displacement of the treated coal gangue subgrade is within 4.0 m below the top of the subgrade, and the maximum displacement value is about 7 mm, which is less than the displacement of untreated coal gangue sample. While the treated A-CG and T-CG grain size, surface area and internal friction angle increase, the unstable carbon structure is destroyed, so its shear strength, compression performance, and consolidation effect are improved. S-CG particles are coated with Na-Si-Al gel, which enhances the density, viscosity and shear strength, thus ensuring the stability of the coal gangue subgrade. The treated coal gangue subgrade slope foot displacement, boundary shear stress and safety factor are all meet the specification requirements.

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 DEVELOPMENT OF A MODEL FOR THE ESTIMATION OF SHEAR STRENGTH OF DISCONTINUITY IN MASSIVE AND KARSTIFIED LIMESTONE

2021 ◽  
Vol 36 (2) ◽  
pp. 43-57
Author(s):  
Ivana Dobrilović ◽  
Petar Hrženjak ◽  
Dražen Navratil
Keyword(s):  
Shear Strength ◽  
Field Research ◽  
Friction Angle ◽  
Roughness Coefficient ◽  
Engineering Practice ◽  
Filling Material ◽  
Dimension Stone ◽  
Large Samples ◽  
Proposed Model ◽  
Made In

In this paper, the problem of estimating the shear strength of discontinuity is presented, which especially occurs in massive and karstified limestones, where discontinuity walls can be extremely rough and irregular, with or without filling material, and for which the current models have proven to be unsatisfactory. A characteristic example of such limestones is the deposit of dimension stone “Kanfanar”, located on the Istrian peninsula in Croatia. For the purpose of developing a model for estimating the shear strength of discontinuity, field research was conducted in which large samples of blocks with natural discontinuities were prepared, as well as samples of filling material in limited conditions, on which detailed laboratory tests of shear strength were performed. Special attention was paid to determining the joint roughness coefficient JRC, the actual contact area between the discontinuity walls, the basic or residual friction angle and the friction angle of the built-in filling material between the discontinuity surfaces. The development of the model for estimating the shear strength of discontinuity was based on Barton’s JRC-JCS empirical model, given the fact that it is one of the most commonly applied models in engineering practice. Based on the results of the tests, a modification of Barton’s JRC-JCS model was made, in such a way that the friction angle of the built-in filling material in the case of discontinuity with a filling was applied instead of the basic or residual friction angle. In addition, for the correct evaluation of the roughness of the discontinuity walls in massive and karstified limestones, it was found that it is necessary to increase the roughness coefficient to values larger than 20, which has been proposed as the maximum so far. Evaluation of the proposed model showed that it is satisfactorily accurate in estimating the shear strength of discontinuity with clay filling material of different states of consistency.

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.

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.

Potential Slip Surfaces of Slope with Strength Parameters

2011 ◽  
Vol 243-249 ◽  
pp. 3315-3318 ◽  
Author(s):  
Hang Lin ◽  
Ping Cao
Keyword(s):  
Shear Strength ◽  
Numerical Analysis ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Slip Surfaces ◽  
Stability Of Slope ◽  
The Stability

The cohesion c and friction angle φ are the main strength parameters influencing the stability of slope. Any of them changes, the factor of safety of slope will change, but it has seldom been considered in the literature how the potential slip surface will change at the same time. In the present paper, the analytical deduction and numerical analysis are done to find out the effect of shear strength parameters c and φ to the distribution of potential slip surface. The study shows that, the potential slip surface is affected by the combination of c and φ, whose function is λ=c/(γhtanφ).

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

scholarly journals Tunnel Back Analysis Based on Differential Evolution Using Stress and Displacement

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joon-Sang An ◽  
Kyung-Nam Kang ◽  
Ju-Young Choi ◽  
Won-Suh Sung ◽  
Vathna Suy ◽  
...  
Keyword(s):  
Differential Evolution ◽  
Differential Evolution Algorithm ◽  
Back Analysis ◽  
Friction Angle ◽  
Internal Displacement ◽  
Average Error ◽  
Analysis Algorithm ◽  
Evolution Algorithm ◽  
Displacement Based ◽  
The Stability

The stability of tunnels has mainly been evaluated based on displacement. Because displacement due to the excavation process is significant, back analysis of the structure and ground can be performed easily. Recently, the length of a segment-lined tunnel driven by the mechanized tunneling method is increasing. Because the internal displacement of a segment-lined tunnel is trivial, it is difficult to analyze the stability of segment-lined tunnels using the conventional method. This paper proposes a back analysis method using stress and displacement information for a segment-lined tunnel. A differential evolution algorithm was adopted for tunnel back analysis. Back analysis based on the differential evolution algorithm using stress and displacement was established and performed using the finite difference code, FLAC3D, and built-in FISH language. Detailed flowcharts of back analysis based on DEA using both monitored displacement stresses were also suggested. As a preliminary study, the target variables of the back analysis adopted in this study were the elastic modulus, cohesion, and friction angle of the ground. The back analysis based on the monitored displacement is useful when the displacement is significant due to excavation. However, the conventional displacement-based back analysis is unsuitable for a segment-lined tunnel after construction because of its trivial internal displacement since the average error is greater than 32% and the evolutionary calculation is finalized due to the maximum iteration criteria. The average error obtained from the proposed back analysis algorithm using both stress and displacement ranged within approximately 6–8%. This also confirms that the proposed back analysis algorithm is suitable for a segment-lined tunnel.

Characterization of Shear Strength and Interface Friction of Organic Soil

2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Friction Angle ◽  
Structural Materials ◽  
Organic Soil ◽  
Internal Friction Angle ◽  
Interface Friction

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

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 Influence of Crack Geometry on Dynamic Damage of Cracked Rock: Crack Number and Filling Material

2020 ◽  
Vol 11 (1) ◽  
pp. 250
Author(s):  
Feili Wang ◽  
Shuhong Wang ◽  
Zhanguo Xiu
Keyword(s):  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Mineral Exploration ◽  
Damage Variable ◽  
Filling Material ◽  
Hopkinson Pressure Bar ◽  
Filling Materials ◽  
The Stability ◽  
Pressure Bar ◽  
Dynamic Damage

The dynamic damage of cracked rock threatens the stability of rock structures in rock engineering applications such as underground excavation, mineral exploration and rock slopes. In this study, the dynamic damage of cracked rock with different spatial geometry was investigated in an experimental method. Approximately 54 sandstone specimens with different numbers of joints and different filling materials were tested using the split Hopkinson pressure bar (SHPB) apparatus. The energy absorption in this process was analyzed, and the damage variable was obtained. The experimental results revealed that the dynamic damage of cracked rock is obviously influenced by the number of cracks; the larger the number, the higher the energy absorption and the bigger the dynamic damage variable. Moreover, it was observed from the dynamic compressive experiments that the energy absorption and the dynamic variable decreased with the strength and cohesion of the filling material, indicating that the filling material of crack has considerate influence on the dynamic damage of cracked rock.

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