scholarly journals Numerical Experiments on Triaxial Compression Strength of Soil-Rock Mixture

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yanxi Zhao ◽  
Zhongxian Liu
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Data Statistics ◽  
Nonlinear Hardening ◽  
Properties Of Soil

Soil-rock mixture is a kind of unfavorable geologic material, and it is composed of low-strength soil particles and high-stiffness rock blocks. Mechanical properties of soil-rock mixture were controlled by the internal mesoscopic medium, thus resulting in great difficulties of determination of mechanical parameters. In this paper, influences of rock content, mesoscopic features, and random distribution of mixture in soil-rock mixture on its shear strength were discussed through discrete element numerical simulation of the laboratory triaxial test. Results demonstrated that, with the increase of rock content, the internal friction angle of soil-rock mixture increased continuously, while the cohesion of soil-rock mixture decreased firstly and then increased. The stress-strain curve belonged to a nonlinear hardening type, which was close to soil characteristic. However, the shear strength was affected by mesoscopic medium of mixture particles significantly, resulting in the strong discreteness of strength, and only by large amounts of data statistics can we get a better regularity of strength. The research results can provide references to determine mechanical parameters of soil-rock mixture.

scholarly journals Shear strength of compacted Chlef sand: effect of water content, fines content and others parameters

2020 ◽  
Vol 42 (1) ◽  
pp. 18-35 ◽  
Author(s):  
Djamel Bouri ◽  
Abdallah Krim ◽  
Abdelkader Brahim ◽  
Ahmed Arab
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Laboratory Study ◽  
Significant Influence ◽  
Mechanical Behaviour ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Fines Content ◽  
Dense State

AbstractThis paper presents a laboratory study of the combined effect of the water content and fines content on the mechanical behaviour of Chlef sand in a medium dense state (RD = 65%) and dense state (RD = 80%). Several mechanical parameters were evaluated such as shear strength, cohesion and friction angle at different water content w = 0, 1, 2 and 3% and different fines content Fc = 0, 10, 20, 30 and 40%. The test results showed that the shear strength of Chlef sand decrease with the increase fines content Fc = 0 to 40%, our tests result also showed that the water content has a significant influence on the shear strength which decreases with the increase in the water content w = 0 to 3%. The fines content and the water content have a significant influence on the mechanical parameters c and φ. Cohesion increases with the percentage of fines and decreases with the increase of the water content while the friction angle decreases with the increase the fines content and the water content.

scholarly journals Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1943
Author(s):  
Fu Yi ◽  
Changbo Du
Keyword(s):  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Strength Index ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Zhang Model ◽  
Triaxial Compression Tests

To evaluate the shear properties of geotextile-reinforced tailings, triaxial compression tests were performed on geogrids and geotextiles with zero, one, two, and four reinforced layers. The stress–strain characteristics and reinforcement effects of the reinforced tailings with different layers were analyzed. According to the test results, the geogrid stress–strain curves show hardening characteristics, whereas the geotextile stress–strain curves have strain-softening properties. With more reinforced layers, the hardening or softening characteristics become more prominent. We demonstrate that the stress–strain curves of geogrids and geotextile reinforced tailings under different reinforced layers can be fitted by the Duncan–Zhang model, which indicates that the pseudo-cohesion of shear strength index increases linearly whereas the friction angle remains primarily unchanged with the increase in reinforced layers. In addition, we observed that, although the strength of the reinforced tailings increases substantially, the reinforcement effect is more significant at a low confining pressure than at a high confining pressure. On the contrary, the triaxial specimen strength decreases with the increase in the number of reinforced layers. Our findings can provide valuable input toward the design and application of reinforced engineering.

scholarly journals Sensitivity Analysis in the Estimation of Mechanical Parameters of Engineering Rock Mass Based on the Hoek–Brown Criterion

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Zhiqiang Li ◽  
Guofeng Liu ◽  
Shuqian Duan ◽  
Shufeng Pei ◽  
Changgen Yan
Keyword(s):  
Rock Mass ◽  
Triaxial Compression ◽  
Damage Zone ◽  
Surrounding Rock ◽  
Geological Strength Index ◽  
Sensitivity Factor ◽  
Mechanical Parameters ◽  
Compression Tests ◽  
Disturbance Factor

Geological strength index GSI, disturbance factor (D), material constant mi, and uniaxial compressive strength σci of the intact rock are essential input parameters IPs of the Hoek–Brown H−B criterion. Mechanical parameters MPs of the engineering rock mass, including elastic modulus E, cohesion c, and internal friction angle φ estimated by the H–B criterion, and the predicted excavation response of surrounding rock, including the displacement and excavation damage zone EDZ based on the MPs, are of high relevance with the four IPs of the H–B criterion. In this paper, the deep and huge underground cavern excavated in basalt from a hydropower station under construction in the southwest of China is used to analyse the sensitivity of the IPs on the MPs, the displacement, and EDZ of the surrounding rock mass. Firstly, the H–B criterion is applied to estimate the MPs, among which the IPs are obtained from a series of in situ and laboratory tests, including borehole camera observation, wave velocity test, uniaxial and triaxial compression tests, and so on. Secondly, the sensitivity relationships between IPs, MPs, and prediction results of displacement and EDZ are established and described quantitatively by the sensitivity factor (si). Results show that the MPs of the rock mass are more sensitive to GSI and D⋅GSI and σci are high-sensitivity parameters affecting the displacement and EDZ. Finally, the variations in the estimated MPs and associated prediction results concerning excavation response, which are caused by the uncertainties in the determination of the IPs, are further quantified. This study provides a straightforward assessment for the variability of the rock mass parameters estimated by the H–B criterion. It also gives a valuable reference to similar geotechnical engineering for the determination of rock mass parameters in the preliminary design.

Influence of Water Contents on Shear Strength of Rammed Earth Wall of Earth-Building

2011 ◽  
Vol 382 ◽  
pp. 172-175
Author(s):  
Ren Wei Wu ◽  
Xing Qian Peng ◽  
Li Zhang
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
World Heritage Site ◽  
Rammed Earth ◽  
Compression Tests ◽  
Rammed Earth Wall ◽  
Influence Of Water ◽  
Water Contents

As the "Fujian earth-building" have been inscribed by UNESCO in 2008 as World Heritage Site, attentions of protection about the "Fujian earth-building" has getting more and more. This article takes samples of a rammed-earth wall from Yongding earth-buildings and determines the shear strength of the samples with different water content through triaxial compression tests. The influence on shear strength of water content of rammed-earth samples is analyzed. Test results show that the shear strength of rammed-earth has much to do with the water content of the soil, the greater the water content is，the smaller the shear strength is. With water content increasing, cohesion and internal friction angle of rammed-earth were decreases, and its changing trend is of marked characteristic of stage. When water contents of rammed-earth is under some value, its cohesion changes in small ranges; when water contents of rammed-earth is over the value, its cohesion decreases with water content increasing.

Experimental Study on Shear Strength Considering Initial Void Ratio and Plasticity Index

2013 ◽  
Vol 405-408 ◽  
pp. 63-67
Author(s):  
Xing Chen Wang ◽  
Ri Qing Xu ◽  
Jian Feng Zhu
Keyword(s):  
Shear Strength ◽  
Void Ratio ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Deviatoric Stress ◽  
Plasticity Index ◽  
Test Results ◽  
Compression Tests ◽  
Functional Relationships ◽  
Initial Void Ratio

A series of drained triaxial compression tests under different conditions were performed to quantitatively study the influence of the initial void ratio and plasticity index on the shear strength of remolded saturated clays. The test results show that both the peak stress friction angle and peak deviatoric stress decrease with increasing initial void ratio and plasticity index of the soil under the same confining pressure; whereas, they increase with increasing confining pressure of the soil under the same initial void ratio and plasticity index. A new synthesized physical parameter λ, which simultaneously represent both the type and the condition of remolded saturated clays, is defined based on the test results in this work. The functional relationships among the parameters φd and peak deviatoric stress in Mohr-Coulomb equation and the parameter λ are established to develop a modified Mohr-Coulomb equation by considering physical properties of soil. In this equation, only two input parameters, i.e., λ and the confine pressure, are needed to predict the shear strength of the soil. In order to check the accuracy of the proposed equation, laboratory tests were conducted to evaluate against the predicted results. The results show that the peak shear strength of remolded saturated clays can be well described by the proposed equation. Key words: shear strength; Mohr-Coulomb equation; remolded saturated clays; initial void ratio; plasticity index.

Determination of the friction angle of soils in triaxial-compression apparatus and shear devices

1985 ◽  
Vol 22 (3) ◽  
pp. 105-111
Author(s):  
A. L. Kryzhanovskii ◽  
Yu. S. Vil'gel'm ◽  
S. V. Medvedev
Keyword(s):  
Triaxial Compression ◽  
Friction Angle

scholarly journals Comparison of Mechanical Properties of Fiber-Reinforced Sand under Triaxial Compression and Direct Shear

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Reza Noorzad ◽  
Seyed Taher Ghoreyshi Zarinkolaei
Keyword(s):  
Shear Strength ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Polypropylene Fiber ◽  
Triaxial Tests ◽  
Direct Shear ◽  
Test Results ◽  
Peak Reduction ◽  
Shear Tests ◽  
Direct Shear Tests

AbstractThis research investigates the behavior of sand reinforced with polypropylene fiber. To do this, 40 direct shear tests and 40 triaxial tests were performed on the coastal beaches of Babolsar, a city in the North of Iran. The effect of parameters such as fiber content, length of fiber and normal or confining pressure on the behavior of Babolsar sand have been studied. In this study, four various fiber contents (0, 0.25, 0.5 and 1 percent), three different lengths of fiber (6, 12 and 18 mm) and four normal or confining pressures (50, 100, 200 and 400 kPa) have been employed. The test results show that fiber inclusion has a significant effect on the behavior of sand. In both direct shear and triaxial tests, the addition of fibers improved shear strength parameters (C, '), increased peak shear strength and axial strain at failure, and also limited the amount of post-peak reduction in shear resistance. The comparison of the test results revealed that due to better fiber orientation toward the direction of principal tensile strain in triaxial test as compared to direct shear tests, the fiber efficiency and its effect on soil behavior is much more significant in triaxial specimens.

scholarly journals X-Ray Microtomography (μCT) as a Useful Tool for Visualization and Interpretation of Shear Strength Test Results

2015 ◽  
Vol 36 (4) ◽  
pp. 47-55 ◽  
Author(s):  
Damian Stefaniuk ◽  
Matylda Tankiewicz ◽  
Joanna Stróżyk
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Soil Testing ◽  
Geometrical Parameters ◽  
Clayey Soils ◽  
Test Results ◽  
Strength Parameters ◽  
X Ray ◽  
Method Of Evaluation

Abstract The paper demonstrates the applicability of X-ray microtomography (ìCT) to analysis of the results of shear strength examinations of clayey soils. The method of X-ray three-dimensional imaging offers new possibilities in soil testing. The work focuses on a non-destructive method of evaluation of specimen quality used in shear tests and mechanical behavior of soil. The paper presents the results of examination of 4 selected clayey soils. Specimens prepared for the triaxial test have been scanned using ìCT before and after the triaxial compression tests. The shear strength parameters of the soils have been estimated. Changes in soil structure caused by compression and shear failure have been presented as visualizations of the samples tested. This allowed for improved interpretation and evaluation of soil strength parameters and recognition of pre-existing fissures and the exact mode of failure. Basic geometrical parameters have been determined for selected cross-sections of specimens after failure. The test results indicate the utility of the method applied in soil testing.

scholarly journals Experimental Studies of Scale Effect on the Shear Strength of Coarse-Grained Soil

2022 ◽  
Vol 12 (1) ◽  
pp. 447
Author(s):  
Shuya Li ◽  
Tiancheng Wang ◽  
Hao Wang ◽  
Mingjie Jiang ◽  
Jungao Zhu
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Scale Effect ◽  
Friction Angle ◽  
Coarse Grained ◽  
Test Results ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Coarse Grained Soil

Shear strength is an essential index for the evaluation of soil stability. Test results of the shear strength of scaled coarse-grained soil (CGS for short) are usually not able to accurately reflect the actual properties and behaviors of in situ CGS due to the scale effect. Therefore, this study focuses on the influence of the scale effect on the shear strength of scaled CGS, which has an important theoretical significance and application for the strength estimation of CGS in high earth-rock dam engineering. According to previous studies, the main cause of the scale effect for scaled CGS is the variation of the gradation structure as well as the maximum particle size (dmax), in which the gradation structure as a characteristic parameter can be expressed by the gradation area (S). A total of 24 groups of test soil samples with different gradations were designed by changing the maximum particle size dmax and gradation area S. Direct shear tests were conducted in this study to quantitatively explore the effect of the gradation structure and the maximum particle size on the shear strength of CGS. Test results suggest that the shear strength indexes (i.e., the cohesion and internal friction angle) of CGS present an increasing trend with the improvement of the maximum particle size dmax, and thus a logarithmic function relationship among c, φ, and dmax is presented. Both cohesion (c) and internal friction angle (φ) are negatively related to the gradation area (S) in most cases. As a result, an empirical relationship between c, φ, and S is established based on the test results. Furthermore, a new prediction model of shear strength of CGS considering the scale effect is proposed, and the accuracy of this model is verified through the test results provided by relevant literature. Finally, the applicability of this model to different types of CGS is discussed.

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