Simulating a direct shear box test by DEM

2006 ◽  
Vol 43 (2) ◽  
pp. 155-168 ◽  
Author(s):  
S H Liu
Keyword(s):  
Contact Angle ◽  
Internal Friction ◽  
Granular Material ◽  
Distinct Element ◽  
Contact Forces ◽  
Interparticle Contact ◽  
Direct Shear ◽  
Angle Of Internal Friction ◽  
Shear Box ◽  
Direct Shear Box Test

Distinct element simulation was performed for direct shear box (DSB) tests on a dense and a loose two-dimensional (2D) sample of 3259 cylinders. Special attention was devoted to the effect that the frictional force between the inside surface of the upper shear box and the sample had on the measured shear strength in the DSB test. Some ways of minimizing this interface frictional force were introduced in the paper. Given that the deformation approximates simple shear within the deforming zone across the sample centre (referred to as the shear zone), a method was proposed to evaluate the overall strains in the DSB test. The numerically simulated data were used to interpret, on a microscopic scale, the angle of internal friction and a 2D stress–dilatancy equation for the mobilized plane in granular material. It was found that the angle of internal friction in granular material is not directly related to the interparticle friction angle (ϕµ). Instead, it relates to the average interparticle contact angle ([Formula: see text]) on the mobilized plane and the ratio k/f0, representing the degree of the probability distribution of the interparticle contact forces that is biased toward the positive zone of the contact angle θ (along the shear direction), where k is the slope of the linear distribution of the average interparticle contact forces against the interparticle contact angle; and f0 is the average interparticle contact force.Key words: angle of internal friction, direct shear box test, distinct element method, friction, granular material, stress–dilatancy.

scholarly journals Shear strength characteristics of Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 74-80
Author(s):  
Talal Masoud
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Content Increase ◽  
Direct Shear ◽  
Initial Water ◽  
Angle Of Internal Friction

The results of the direct shear test on Jerash expansive soil show the effect of the initial water content on the cohesion (c) and on the angel of internal friction ( ) [shear strength parameters].it show that, as the initial water increase, the cohesion (c) of Jerash expansive soil also increase up to the shrinkage limit, after that increase of water even small amount, decrease the cohesion of the soil. On the other hand, the results of direct shear test show also  that as the water content increase, the angle of internal friction ( )remain unchanged up to shrinkage limit , any increase of water cause a large decrease on the angle of internal friction of Jerash expansive soil.

Reliability of Shear-Box Tests Upon Soaking Process on the Sand Soil in Al-Najaf City

2020 ◽  
Vol 857 ◽  
pp. 212-220
Author(s):  
Mohammed Sh. Mahmood ◽  
Waseem H. Al-Baghdadi ◽  
Asaad M. Rabee ◽  
Suhad H. Almahbobi
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Sandy Soil ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Engineering Structures ◽  
Angle Of Internal Friction ◽  
Shear Box ◽  
Testing Condition ◽  
Direct Shear Apparatus

Accurate prediction of the soil shear strength parameters is essential in the reliable geotechnical design of civil engineering structures. This recent paper investigates the effect of the dry testing condition on the shear strength parameters of the sandy soil using the direct shear apparatus and compared with the saturated condition tests in previous researches on the same soil. The dry soil, usually above the water table, is the principal condition of the Al-Najaf city soil in Iraq. Samples are selected from the site of the University of Kufa, which represents the sandy soil of the city. For reliability purposes, the soil is exposed to different pre-soaking durations (one, two, and four weeks) then air-dried for shear tests. The main results revealed that the angle of internal friction (Φ) tested as a dry sample decreases about -6% up to two-weeks soaking then recovered upon four-week soaking about +6%. Compared to the saturated testing, there are increases in F between 6%-17% from saturated tests. Finally, it is recommended to aware in the selection of testing conditions for calculations of the angle of internal friction.

scholarly journals Direct Shear Strength on the São Francisco River Bank, Northeastern Brazil, With or Without Roots of Different Native Species

2020 ◽  
Vol 9 (1) ◽  
pp. 146
Author(s):  
Igor Pinheiro da Rocha ◽  
Francisco Sandro Rodrigues Holanda ◽  
Mario Monteiro Rolim ◽  
Alceu Pedrotti ◽  
Marks Melo Moura ◽  
...  
Keyword(s):  
Internal Friction ◽  
Native Species ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Northeastern Brazil ◽  
Degree Of Saturation ◽  
Void Content ◽  
Direct Shear ◽  
River Bank ◽  
Angle Of Internal Friction

Several plant species have been studied as reinforcement elements against landslides at slopes, either to protect against the splash effect offered by shoots or anchoring the soil by the root system. The objective of this work was to investigate the influence of roots from shrub species over the soil mechanical attributes such as cohesion and angle of internal friction at the São Francisco riverbank, northeastern Brazil. A trench was excavated under the treetop of every shrubby individual, sampling blocks at 0-0.25, 0.25-0.50, 0.50-0.75, and 0.75-1.00 m depths. The moisture contents, particle size, liquidity limits, plasticity and actual specific mass of the samples were determined. The soil physical and mechanical attributes such as initial and final specific weight, initial and final void content, initial and final degree of saturation, shear resistance peaks, cohesion, and internal friction angle were identified through direct, elementary, consolidated, and undrained tests. In the samples with Solanum paniculatum, Mimosa pigra species, the highest values for cohesion were registered for the samples with roots. Sesbania virgata presented the greatest variation in cohesion and internal friction angle among samples with and without roots. The position and root status influenced the results of the direct shear tests.

Experimental Study on Shear Strength of Expansive Soil Improved by Lime - Weathered Sand

2013 ◽  
Vol 446-447 ◽  
pp. 1441-1447
Author(s):  
Meng Yun Huang ◽  
Jun Lai Xiong ◽  
Ji Bing Tang ◽  
Chi Long
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Dry Density ◽  
Direct Shear ◽  
Mass Ratio ◽  
Angle Of Internal Friction ◽  
The Impact

This paper ananlyzes and contrasts the direct shear test of the expansive soil with different weathered sand dosage (mass ratio) and different lime dosage (mass ratio) in the case of the expansive soil with some water content and dry density .And try to analyzes and researches the impact of expansive soil improved by weathered sand and lime shear strength index . The direct shear test by the expansive soil mixed with different proportions of weathered sand and lime can be concluded that: mixing the weathered sand to improve the shear strength of expansive soil is effective, and cohesion gradually decreases with the increase of doped proportion of sand and the angle of internal friction first increases with the increase of doped proportion of sand and then decreases ;mixing of lime is effective to improve the shear strength of expansive soil, and cohesion gradually decreases with the increase of doped proportion of lime and angle of internal friction first increases and then decreases with the increase of doped proportion of lime. The shear strength of improved expansive soil can meet the subgrade filling with soil standards and at the same time the expansive soil improved by weathered sand and lime reduces the amount of lime and reduce project cost when to achieve the same shear strength standards.

Effect of Sample Size on TDA Shear Strength Parameters in Direct Shear Tests

2020 ◽  
Vol 2674 (9) ◽  
pp. 1110-1119 ◽  
Author(s):  
Khaled Zahran ◽  
Hany El Naggar
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Shear Tests ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Direct Shear Tests ◽  
Shear Box ◽  
Box Dimensions

Tire-derived aggregate (TDA), a relatively new construction material, has been gaining acceptance as a backfill material for embankments, trenches, and earth-retaining structures because of its lightweight and excellent geotechnical properties. Type A TDA has a basic geometric shape, with particles approximately 12 to 100 mm in size. As a result of the simplicity and accuracy of the direct shear test, most laboratories choose this test in preference to more complex tests. However, TDA requires large-scale direct shear apparatus because of the consistently large size of its particles, and few facilities own this type of apparatus. Depending on the shear box dimensions, the aspect ratio of the particle size to the box dimensions may lead to variations in the shear strength results of the sample being evaluated. This research focuses on studying the effect of TDA sample size on the shear strength results of direct shear tests by using five different shear box sizes. The findings show that the angle of internal friction increases slightly as the dimensions of the shear box decrease. It was found that the maximum variation in the angle of internal friction and the cohesion results of the different shear boxes was only 1.9° and 2.4 kPa, respectively. These differences should be taken into consideration when TDA shear test results are used in the geotechnical design. It is recommended that a shear box with an aspect ratio (W/Dmax) greater than or equal to 4 should be used when evaluating the shear strength parameters of TDA.

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