Experimental and Numerical Evaluation of the Parameters Influencing the Shear-Stress Behavior of Interlocking Paver Blocks–Bedding Sand Interface Using Large-Scale Direct Shear Test

2021 ◽  
Vol 33 (6) ◽  
pp. 04021104
Author(s):  
Arjun Siva Rathan Raveendran Thulasibai ◽  
Sunitha Velayudhan ◽  
Murshida Pathath ◽  
Janani Lekshmipathy ◽  
Anusudha Visvanathan
Author(s):  
Jakub Stacho ◽  
Monika Sulovska ◽  
Ivan Slavik

The paper deals with the laboratory testing of coarse-grained soils that are reinforced using a geogrid. The shear strength properties were determined using a large-scale direct shear test apparatus. The tests were executed on original as well as on reinforced soil, when the geogrid was placed on a sliding surface, which permitted determining the shear strength properties of the soil-geogrid interface. The aim of the tests was to determine the interface shear strength coefficient α, which represents the ratio of the shear strength of the soil-geogrid interface to the unreinforced soil. The tests were executed on 3 samples of coarse-grained materials, i.e., poorly graded sand, poorly graded fine gravel and poorly graded medium gravel. Two types of geogrids were tested, i.e., a woven polyester geogrid and a stiff polypropylene geogrid. The results of the laboratory tests on the medium gravel showed that the reduction coefficient α reached higher values in the case of the stiff polypropylene geogrid. In the cases of the fine gravel and sand, the values of the interface coefficient α were similar to each other. The shear strength of the interface was reduced or was similar to the shear strength of unreinforced soil in a peak shear stress state, but significantly increased with horizontal deformations, especially for the fine gravel and sand. The largest value of the coefficient α was measured in the critical shear stress state. Based on the results of the testing, a correlation which allows for determining the optimal grain size distribution was obtained.


2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhuoling He ◽  
Junyun Zhang ◽  
Tao Sun

With the steady development of the development of the western region in China, the construction of mountain highways has developed rapidly, and the soil-rock mixed filler, as an excellent filler, is widely used in the subgrade filling of mountain highways. Unlike ordinary fine-grained soil, the source of the soil-rock mixtures (S-RMs) is not unique, and the particle size difference is large and the water content is not uniform, resulting in very complicated mechanical properties. But the current highway embankment codes are still mainly established on the fine-grained soil. It is not fully applicable to soil-rock filled embankment. Based on soil-rock filled embankment engineering practice, this research uses a large-scale direct shear test to research the mechanical characteristics of the S-RMs with different maximum particle diameters. According to the large-scale direct shear test of S-RMs with different maximum particle diameters, the shear displacement vs shear stress curve, shear dilation, and strength characteristics with maximum particle diameter were analyzed. Results demonstrate that whether secondary hardening occurs mainly depends on the normal stress and the maximum particle diameter of the filler. At different maximum particle diameters, the horizontal displacement vs vertical displacement curves of the S-RMs can be roughly divided into continuous shearing and beginning of shearing and quick dilation. And the shear strength increases with the increase of the maximum particle diameter. Moreover, the cohesion decreases first and then increases with the increase of the maximum particle diameter, and the internal friction angle increases with the increase of the maximum particle diameter. Therefore, some RBs with large particle diameter added to filler can effectively improve the shear strength of the S-RMs, which may be valuable for realistic engineering.


2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Longqi Liu ◽  
Xuesong Mao ◽  
Yajun Xiao ◽  
Qian Wu ◽  
Ke Tang ◽  
...  

The mechanical strength of the landslide deposits directly affects the safety and operation of the roads in the western mountainous area of China. Therefore, the research is aimed at studying the mechanisms of a landslide deposit sample with different rock particle contents by analyzing its characteristics of the stress-strain behavior, the “jumping” phenomenon, the volumetric strain, and the shear strength parameters via a large-scale direct shear test. Stress-strain results show that stress-strain curves can be divided into 3 different stages: liner elastic stage, yielding stage, and strain-hardening stage. The shear strength of SRM behaves more like “soil” at a lower rock particle content and behaves more like “rock joints” at a higher rock particle content. Characteristics of the “jumping” phenomenon results show that the “intense jumping” stage becomes obvious with the increasing rock particle content and the normal stress. However, the lower the rock particle content is, the more obvious the “jumping” phenomenon under the same normal stress is. Volumetric strain results show that the sample with a lower rock particle content showed a dilatancy behavior under the low normal stress and shrinkage behavior under the high normal stress. The dilatancy value becomes smaller with the increasing normal stress. The maximum shear stress value of the rock particle content corresponds to the maximum value of dilatancy or shrinkage. We also conclude that the intercept of the Mohr failure envelope of the soil-rock mixture should be called the “equivalent cohesion,” not simply called the “cohesion.” The higher the normal stress and rock particle content are, the bigger the equivalent cohesion and the internal friction angle is.


2020 ◽  
Vol 165 ◽  
pp. 04079
Author(s):  
B Li

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.


2016 ◽  
Vol 143 ◽  
pp. 1007-1015 ◽  
Author(s):  
M. Mahdi Biabani ◽  
Buddhima Indraratna ◽  
Sanjay Nimbalkar

Author(s):  
Yanhai Wang ◽  
Jianlin Li ◽  
Qiao Jiang ◽  
Yisheng Huang ◽  
Xinzhe Li

The soil-rock mixture (SRM) is a kind of special engineering geological material, which has been exposed to the field for a long time and is affected by rainwater seepage, geological force, slope sliding force and human activities, resulting in the spatial variability of its mechanical properties. Taking the SRM distributed on a slope of the Three Gorges Reservoir area as the research object, four test locations were selected along and transverse the slope. First, in-situ large-scale direct shear test was carried out, and then the laboratory large-scale direct shear test, particle sieving test, and water content test were carried out in the undisturbed sample to study the variation of shear mechanical properties of SRM distributed in different spatial locations. The results show that: (1) Under the same normal stress, the peak strength of the SRM decreases at a similar rate along the slope direction and the transverse slope direction. (2) The cohesion of the SRM is continuously strengthened, and the friction angle is continuously deteriorated along the slope from high to low, the cohesion and friction angle are almost no variability along the transverse slope. (3) The mechanism of the above-mentioned variation in the shear mechanics parameters of SRM is that the lower the elevation along the slope, the more fragmented the rock, the lower the rock content. (4) Spatial variability models of cohesion and friction angle of SRM were established, which can provide references for related engineering applications.


2018 ◽  
Vol 7 (3) ◽  
pp. 1768
Author(s):  
Aram Mohammed Raheem

In this study, an experimental and numerical investigation of Kirkuk real field soil treated with waste tire has been examined. Field soil samples from Kirkuk city have been collected and tested experimentally to evaluate the basic soil properties. The field soil has been treated with waste shredded tires and up to 10%. A series of direct shear tests under different normal stresses and unconfined compression tests with two different rates have been performed on both untreated and waste tire treated soils. For the untreated soil, the maximum shear stress measured by the direct shear test increased by 150% when the normal shear stress increased from 50 kPa to 150 kPa. For the 5% and 10% waste tire treated soils, the maximum shear stresses measured by the direct shear test increased by 110% and 105% when the normal stress increased from 50 kPa to 150 kPa respectively. The peak uniaxial stress measured by the unconfined compression test increased by 83% and 98% as the waste tire treatment increased from 0% to 10% for both testing rates of 0.125 mm/min and 0.25 mm/min respectively. Finally, finite element method using three different models represented by elastic, hyperbolic and Mohr-Coulomb elastic-plastic models have been used to model unconfined compression tests for both untreated and 10% waste tire treated soils. For both untreated and waste tire treated soils, the elastic model over predicted the shear stress versus shear strain relationship whereas the elastic-plastic model had a very good agreement with the experimental data. However, the hyperbolic model had a good prediction for the initial part of the shear stress versus shear strain relationship for both untreated and waste tire treated soils with an overestimation for the second part of the experimental data.  


Sign in / Sign up

Export Citation Format

Share Document