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.

scholarly journals Experimental Study of the Composition and Structure of Granular Media in the Shear Bands Based on the HHC-Granular Model

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Guang-jin Wang ◽  
Xiang-yun Kong ◽  
Chun-he Yang
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Granular Media ◽  
Random Distribution ◽  
Shear Bands ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Coarse Grained ◽  
Composition And Structure ◽  
Coarse Grained Soil

The researchers cannot control the composition and structure of coarse grained soil in the indoor experiment because the granular particles of different size have the characteristics of random distribution and no sorting. Therefore, on the basis of the laboratory tests with the coarse grained soil, the HHC-Granular model, which could simulate the no sorting and random distribution of different size particles in the coarse-grained soil, was developed by use of cellular automata method. Meanwhile, the triaxial numerical simulation experiments of coarse grained soil were finished with the different composition and structure soil, and the variation of shear strength was discussed. The results showed that the internal friction angle was likely to reduce with the increasing of gravel contents in the coarse-grained soil, but the mean internal friction angle significantly increased with the increment of gravel contents. It indicated that the gravel contents of shear bands were the major factor affecting the 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.

Study on the Granular Shear Strength Parameters of Dumping Site

2012 ◽  
Vol 256-259 ◽  
pp. 358-361
Author(s):  
Xiang Yun Kong ◽  
Guang Jin Wang ◽  
Xiao Chao Zhou
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Dumping Site ◽  
Size Grading

Apparent particle size grading is the important characteristic of super-high bench dumping site, and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of granular. With the copper mine dumping site which had the feature of apparent particle size grading, the thesis carried out the study of on-site particle size investigation and indoor laboratory. The particle-size distribution law with the changing of dumping-site height was analyzed and quantitative relationship between the fragmentation distribution and shear strength parameters of granular was discussed. The research results indicated that coarse-grain contents and maximum grain size were increased significantly according to the decreasing of dumping-site height, which showed that the dumping-site had the feature of apparent particle size grading. The coarse particle content in the grain size composition and internal friction angle φ of shear strength parameters increased with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ could be expressed by exponential function curve.

Numerical Simulation of Triaxial Tests for Coarse-Grained Soil Considering the Initial Fabric of Samples Grain

2010 ◽  
Vol 143-144 ◽  
pp. 873-878
Author(s):  
Guang Jin Wang ◽  
Xiang Yun Kong ◽  
Yi Lei Gu ◽  
Chun He Yang
Keyword(s):  
Numerical Simulation ◽  
Internal Friction ◽  
Random Distribution ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Strength Parameters ◽  
The Relationship ◽  
Coarse Grained Soil

The strength parameters of granular coarse-grained soil are the critical factor that affects the stability of ultra-high dump. The soil particles of different size have no sorting and random distribution, which leads to the initial fabric of sample grain uncontrolled in the laboratory test of coarse-grained soil, therefore, only relying on the laboratory testing is difficult to obtain the reliable strength parameters of coarse-grained soil. Based on Cellular Automata method, combining the laboratory triaxial tests of coarse-grained soil developed the HHC-CA model which generated the coarse-grained soil samples of different initial fabric of grain to characterize the heterogeneous and random distribution of coarse-grained soil grain group. Then by means of FLAC3D, conducting triaxial numerical simulation tests of coarse-grained soil and discussing the relationship between the gravel contents of samples shear band and samples and internal friction angle. Moreover, the shear strength model for different coarse-grained contents is established. Numerical simulation results indicated that the relationship between internal friction angle of coarse-grained soil and gravel contents of samples shear band were increasing function in the same size grading. According to the increasing of samples gravel contents, the internal friction angle might reduce, but the mean internal friction angle significantly increased with the increment of samples gravel contents.

scholarly journals Study on Shear Properties of the Soil-rock Mixture

2020 ◽  
Vol 165 ◽  
pp. 04079
Author(s):  
B Li
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Direct Shear ◽  
Shear Properties ◽  
Maximum Particle Size ◽  
Maximum Particle

In order to study the shear properties of the soil-rock mixture, a large-scale indoor direct shear test is used to test the shear strength (τ) of SRM under different positive pressures, and calculates the internal friction angle (φ) and cohesive force (c) according to the molar theory. The effects of soil-rock ratio, gradation, maximum particle size, moisture content, and compaction on the shear properties of the soil-rock mixtures are studied. The results show that as the soil-rock ratio decreases, the τ and φ of the SRM increase, while the c increases first and then decreases, and reaches the maximum peak when the soil-rack ratio is 40:60. As the maximum particle size increases, the τ and φ of the SRM increase, while the c decreases. With the increase of the moisture content, the τ, φ and c of the SRM all increase first and then decrease, and reach the maximum peaks when the moisture content is 10.5%, 10%, and 12%, respectively. With the increase of compaction, the τ, φ and c of SRM all increase. The effect of gradation on τ, φ and c is small.

Advanced studies on coal injection into a cavitation cell for the purpose of comminution / Badania procesu wtłaczania węgla do komór kawitacyjnych w celu rozdrabniania

2012 ◽  
Vol 57 (3) ◽  
pp. 769-778
Author(s):  
Greg Galecki ◽  
Gul Akar ◽  
Sezai Sen ◽  
Yaqing Li
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Surface Area ◽  
Back Pressure ◽  
Closed Circuit ◽  
Test Results ◽  
Particle Size Reduction ◽  
Maximum Particle Size ◽  
Coal Injection ◽  
Maximum Particle

Abstract In this study, the effect of coal comminution with waterjets enhanced by cavitation was investigated. The experiments were carried out using mono-size coal feeds in a batch closed circuit, in a specially designed cell to induce cavitation at 69 MPa inlet pressure and back pressures of zero and 0.345 MPa. Test results were evaluated on the product calculated surface area and the Rosin-Rammler parameters. The experiments showed that the maximum particle size reduction was achieved during the first run through the comminution circuit operated without back pressure. However, a decreasing tendency in comminution efficiency was noted with the number of runs through the system. The use of 0.345 MPa back pressure resulted in a wider size distribution of the product.

scholarly journals Effect of the Particle Size on the TDA Shear Strength and Stiffness Parameters in Large-Scale Direct Shear Tests

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Hany El Naggar ◽  
Khaled Zahran ◽  
Ahmed Moussa
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Large Scale ◽  
Fire Hazard ◽  
Unit Weight ◽  
Direct Shear ◽  
Large Area ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Strength And Stiffness

The increase in the number of discarded tires every year is becoming a major issue all over the world. Tires stockpiles and landfills have become a critical issue as they are considered a fertile environment for the breeding of rats and insects, a real fire hazard that may take up to months to extinguish and occupy a valuable, large area of land. One of the safest effective ways of recycling tires is that to use them as backfilling material, among different usages, in civil engineering projects due to their low unit weight and specific gravity. However, to use any material in the construction industry, several material properties must be evaluated, including the shear strength and stiffness parameters. Many factors control the measured parameters. One main factor that is known to have a significant effect is the particle size. This paper focuses on evaluating the effect of the particle size on the shear strength and stiffness parameters of six tire-derived aggregate (TDA) samples having particle sizes range between (9.5–101.6 mm) using a large-scale direct shear machine. The tests were conducted under three normal stresses: 50.1, 98.8 and 196.4 kPa using a constant shearing rate of 0.5 mm/min. The results of this study showed an increasing angle of internal friction as the maximum particle size increases. Moreover, the secant shear modulus also exhibited an increase by increasing the maximum particle size. Furthermore, equations to estimate the stress-strain curves of Type A-TDA for different confidence levels were developed, and their predictions were compared with experimental results to assess their suitability.

scholarly journals Effect of the Particle Size on TDA Shear Strength Parameters in Triaxial Tests

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 76
Author(s):  
Hany El Naggar ◽  
Khaled Zahran
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Large Scale ◽  
Triaxial Tests ◽  
Backfill Material ◽  
Maximum Particle Size ◽  
Key Factor ◽  
Confining Pressures ◽  
Maximum Particle ◽  
Strength And Stiffness

Tire recycling and reuse in North America and worldwide have increased considerably, intending to reduce the harmful effects of scrap tires on the environment. Accordingly, the use of tire derived aggregates (TDA) as backfill material in civil engineering applications is on the rise at an unprecedented rate. However, to use TDA in the construction industry, its strength and stiffness parameters properties must be evaluated. One key factor that is known to influence the strength and stiffness of backfill material is the particle size of the used material. Hence, in this paper, a series of large-scale triaxial tests on five TDA samples with different maximum particle size, Dmax, of 19.05, 25.4, 38.1, 50.8 and 76.2 mm were conducted to investigate the effect of the particle size on the obtained results. The tests were done under consolidated drained conditions using three confining pressures of 50, 100, and 200 kPa. The results showed that the shear strength of TDA increase by increasing the maximum particle size while the cohesion did not show a specific trend. Moreover, the samples exhibited an increase in the secant elastic modulus by increasing the particle size.

Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

2021 ◽  
pp. 136943322110179
Author(s):  
DongTao Xia ◽  
ShaoJun Xie ◽  
Min Fu ◽  
Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

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.

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