Adjustment of rock mass strength parameters using direct shear tests carried out on large blocks

2013 ◽  
pp. 175-180
Author(s):  
G Zapata ◽  
A Assis
Keyword(s):  
Rock Mass ◽  
Direct Shear ◽  
Shear Tests ◽  
Strength Parameters ◽  
Rock Mass Strength ◽  
Direct Shear Tests

Study of Shear Constitutive Model for Schistose Rock Mass

2013 ◽  
Vol 838-841 ◽  
pp. 800-804
Author(s):  
Shang Ge Liu ◽  
Hua Xu ◽  
Jian Liu ◽  
Xiao Tao
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Engineering Practice ◽  
Direct Shear ◽  
Shear Tests ◽  
Peak Displacement ◽  
Direct Shear Tests ◽  
Advantages And Disadvantages ◽  
Piecewise Exponential ◽  
Water Saturated

Based on the direct shear tests of schist and shale at dry and water-saturated states, combed with the advantages and disadvantages of models for rock mass and structure surface, we proposed shear stress-displacement constitutive model of schistose rock mass. The model is in the form of piecewise exponential function and its advantages are as follows: Piecewise function can reasonably describe the nonlinear pre-peak shear hardening and post-peak shear softening characteristics; Regard peak strength, peak displacement and residual strength as critical points, so it can accurately describe the strength characteristics of the material; The fitting degree is high with direct shear tests both at dry and water-saturated states; Only one parameter value is needed to obtain by fitting experimental curves while others are convenient to determine. All of those are benefit to applications in engineering practice.

scholarly journals Mechanical Behaviour of Reinforced Sand with Natural Curauá Fibers through Full Scale Direct Shear Tests

2019 ◽  
Vol 92 ◽  
pp. 12003
Author(s):  
Leila Maria Coelho de Carvalho ◽  
Michelé Dal Toé Casagrande
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Soil Reinforcement ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Shear Tests ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Soil Shear Strength ◽  
Curaua Fibers

Inclusion of natural fibers (sisal, curauá, coco fiber and others) for soil improvement has been the study object in diverse geotechnical areas and it is a topic of growing interest, within the research area of new geotechnical materials. The state of the art in this subject highlights excellent results as soil strength parameters improve and post-cracking strength (toughness) increase. Soil reinforcement technique with fibers is established in the technology of composite materials, this being a combination of two or more materials presenting properties that the component materials do not possess on their own. The aim of this paper is to study the mechanical behaviour of sand-fiber composite by inserting natural curauá fibers into a sandy matrix, with different fiber contents. The fibers were randomly distributed in the soil mass. The experimental program included physical and mechanical characterization of the composites, using full-scale direct shear tests, with samples measuring 30 x 30 cm and 15 cm high. Direct shear tests were carried out using fibers with 25 mm length and 0.5 and 0.75% fiber content (relative to the soil dry weight). The specimens also presented a relative density of 50% and moisture content of 10%. It was sought to establish a pattern behaviour so that the addition of curauá fiber influence can be explained, thus, comparing with the sandy soil shear strength parameters. Inclusion of natural curauá fibers as soil reinforcement presented satisfactory results, as an increase in the soil shear strength parameters was observed when compared with sandy soil results.

Evaluation of the anisotropy and directionality of a jointed rock mass under numerical direct shear tests

2017 ◽  
Vol 225 ◽  
pp. 29-41 ◽  
Author(s):  
Peitao Wang ◽  
Fenhua Ren ◽  
Shengjun Miao ◽  
Meifeng Cai ◽  
Tianhong Yang
Keyword(s):  
Rock Mass ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

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.

scholarly journals Sand- and Clay-Photocured-Geomembrane Interface Shear Characteristics Using Direct Shear Test

2021 ◽  
Vol 13 (15) ◽  
pp. 8201
Author(s):  
Lihua Li ◽  
Han Yan ◽  
Henglin Xiao ◽  
Wentao Li ◽  
Zhangshuai Geng
Keyword(s):  
Soil Surface ◽  
Friction Angle ◽  
Direct Shear ◽  
Tensile Crack ◽  
Shear Tests ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Carbon Black Powder ◽  
Shear Characteristics ◽  
Impermeable Layer

It is well known that geomembranes frequently and easily fail at the seams, which has been a ubiquitous problem in various applications. To avoid the failure of geomembrane at the seams, photocuring was carried out with 1~5% photoinitiator and 2% carbon black powder. This geomembrane can be sprayed and cured on the soil surface. The obtained geomembrane was then used as a barrier, separator, or reinforcement. In this study, the direct shear tests were carried out with the aim to investigate the interfacial characteristics of photocured geomembrane–clay/sand. The results show that a 2% photoinitiator has a significant effect on the impermeable layer for the photocured geomembrane–clay interface. As for the photocured geomembrane–sand interface, it is reasonable to choose a geomembrane made from a 4% photoinitiator at the boundary of the drainage layer and the impermeable layer in the landfill. In the cover system, it is reasonable to choose a 5% photoinitiator geomembrane. Moreover, as for the interface between the photocurable geomembrane and clay/sand, the friction coefficient increases initially and decreases afterward with the increase of normal stress. Furthermore, the friction angle of the interface between photocurable geomembrane and sand is larger than that of the photocurable geomembrane–clay interface. In other words, the interface between photocurable geomembrane and sand has better shear and tensile crack resistance.

Sign in / Sign up

Export Citation Format

Share Document