Experimental investigation of the system normal stiffness of a 5 MN direct shear test setup and the compensation of it in CNS direct shear tests

The interface of non-woven geotextile and HDPE geomembrane based on direct shear test has an obvious softening behavior. This paper adopts displacement-softening model that proposed by Esterhuizen and conducts secondary development by using ABAQUS and its embedded FRIC subroutine, making further efforts to conduct numerical simulation of interface of non-woven geotextile and HDPE geomembrane based on large-size direct shear tests. Results show that the developed interface friction model can simulate the characteristics of interface softening of certain materials better, thus providing a method when study the interface softening characteristic of materials.

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Reliability Analysis of a Direct Shear Test of Modified Iron Tailings Based on the Monte Carlo Algorithm

Advances in Civil Engineering ◽

10.1155/2020/8897094 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Ping Jiang ◽

Jian Qian ◽

Na Li

Keyword(s):

Monte Carlo ◽

Direct Shear Test ◽

Shear Test ◽

Friction Angle ◽

Direct Shear ◽

Shear Tests ◽

Type Curve ◽

Direct Shear Tests ◽

Thaw Cycle ◽

Freeze Thaw Cycle

The resource utilization of iron tailings is of great significance for all countries in the world. Considering the particle composition and physicochemical characteristics of iron tailings, fiber and lime were used to modify iron tailings. The fiber content was 0%, 0.25%, 0.5%, 0.75%, and 1%, and the lime content was 0%, 2%, 4%, 8%, and 10%, respectively. Through a direct shear test, the shear stress displacement (τ-δ) curves and shear strength of modified iron tailings, under the action of a 0 freeze-thaw cycle and 1 freeze-thaw cycle, were tested. As statistics have shown that there are uncertainty factors associated with direct shear tests, the shear strength index cohesion c and internal friction angle φ of the modified iron tailings were analyzed using the Monte Carlo method. The results show that the τ-δ curve of the fiber-modified iron tailings is a hardening-type curve and that of the lime-modified iron tailings is a softening-type curve. In the direct shear tests, the main uncertain factors are the specimen diameter, vertical force, and horizontal force. The diameter of the sample obeys a normal distribution, and the vertical and horizontal forces obey a uniform distribution. The results of the Monte Carlo simulation show that both c and φ obey a normal distribution. Under a 95% confidence condition, the effect of fiber on the cohesion on iron tailings is obvious, but the effect on the internal friction angle is not obvious. However, the values of c and φ of the iron tailings are clearly improved by lime. Additionally, the iron tailings modified by a fiber content of 1% and those modified by a lime content of 8% have the best frost resistance.

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Determination of the Effect of Soil Particle Size Distribution on the Shear Behavior of Sand

Journal of Advanced Engineering and Computation ◽

10.25073/jaec.202152.331 ◽

2021 ◽

Vol 5 (2) ◽

pp. 125

Author(s):

Mohammad Afrazi ◽

Mahmoud Yazdani

Keyword(s):

Particle Size ◽

Shear Strength ◽

Direct Shear Test ◽

Shear Test ◽

Friction Angle ◽

Particle Sizes ◽

Direct Shear ◽

Shear Tests ◽

Direct Shear Tests

Many geotechnical problems require the determination of soil engineering properties such as shear strength. Therefore, the determination of the reliable values for this parameter is essential. For this purpose, the direct shear test, as one of the oldest tests to examine the shear strength of soils, is the most common way in laboratories to determine the shear parameters of soil. There are far too many variables that influence the results of a direct shear test. In this paper, a series of 10 × 10 cm direct shear tests were carried out on four different poorly graded sands with different particle size distributions to determine their shear behaviors. Four different poorly graded sands with a different median diameter or medium value of particle size distribution (D50) (0.2, 0.53, 1.3, and 2.3 mm) has been selected, and about 40 direct shear tests were conducted. It was concluded that a soil’s friction angle is affected by coarse-grained material. Accordingly, sandy soils with bigger particle sizes record a higher friction angle than soils containing small particles. The investigations also showed that sand with bigger particle sizes has a higher dilation angle. In addition, a non-linear regression analysis was performed to establish the exact relationship between the friction angle of the soil and the characteristics of the soil particles. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Sustainability ◽

10.3390/su12072836 ◽

2020 ◽

Vol 12 (7) ◽

pp. 2836

Author(s):

Yunlong Guo ◽

Yameng Ji ◽

Qiang Zhou ◽

Valeri Markine ◽

Guoqing Jing

Keyword(s):

Direct Shear Test ◽

Shear Test ◽

Dynamic Performance ◽

Experimental Tests ◽

Discrete Element ◽

Crumb Rubber ◽

Discrete Element Modelling ◽

Direct Shear ◽

Shear Tests ◽

Direct Shear Tests

The rubber-protected ballast (RPB) is made from natural ballast particles and crumb rubber particles. The crumb rubber is shredded waste tires. RPB was chosen to replace the ballast as it has higher resistance to breakage and abrasion. However, the static and dynamic performance of the RPB has not been confirmed yet. Towards this end, experimental tests and numerical simulations were utilized to study the feasibility of RPB application. Direct shear tests (DSTs) were performed and a DST model and three-sleeper track model with the discrete element method (DEM) were built. The shear strength, settlement, displacement, and acceleration of the RPB were studied. The results show that the RPB has the advantage of increasing the force (stress) distribution and that the smaller crumb rubber size was more suitable for replacing the ballast particles.

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Direct Shear Test of Unsaturated Soil

Earth Sciences Research Journal ◽

10.15446/esrj.v21n4.66103 ◽

2017 ◽

Vol 21 (4) ◽

pp. 183-188

Author(s):

Peng He ◽

Liuying Sun ◽

Zhen Wang

Keyword(s):

Shear Strength ◽

Unsaturated Soil ◽

Direct Shear Test ◽

Shear Test ◽

Test Scheme ◽

Direct Shear ◽

Shear Strength Parameters ◽

Shear Tests ◽

Direct Shear Tests ◽

Good Agreement

The present study focuses on some tentative laboratory tests using a newly-constructed modified direct shear test apparatus. The single-stage and multistage direct shear tests were performed to determine the shear rate and test scheme of unsaturated shear test. Shear strength parameters of unsaturated soil in different conditions are obtained and the tests indicate good agreement with typical theories of unsaturated soil, the nonlinear matric suction failure envelope is determined. Some shear strength equations are also fitted through the experimental results.

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Effects of Clay and Moisture Content on Direct Shear Tests for Clay-Sand Mixtures

Advances in Materials Science and Engineering ◽

10.1155/2013/562726 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 43

Author(s):

Muawia A. Dafalla

Keyword(s):

Internal Friction ◽

Moisture Content ◽

Direct Shear Test ◽

Shear Test ◽

Horizontal Displacement ◽

Direct Shear ◽

Shear Tests ◽

Angle Of Internal Friction ◽

Direct Shear Tests ◽

Moisture Contents

The direct shear test using shear box is commonly recommended by practicing geotechnical engineers to obtain the cohesion and angle of internal friction for granular soils. The clay liners involve sand as a main constituent with added clay of variable proportions. This research aims at investigating the reliability of using the direct shear test for different clay contents and different moisture contents using an adequate shearing strain. These factors were found to affect the bilinear trends of shear force versus horizontal displacement profile as well as vertical displacement versus horizontal displacement curves. The cohesion of the mixture was found to increase consistently with the increase of clay content. Increase in moisture content was found to cause a drop in both cohesion and angle of internal friction. These changes are not independent of the density state of clay-sand mixtures. Standard compaction properties for a range of clay-sand mixtures were investigated. This work provides the general trends expected in direct shear tests for clay-sand mixtures of variable clay and moisture contents.

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