scholarly journals Development of an Automated Cyclic Direct Shear Test Apparatus for Determining Strength Parameters for Landslide Slope Stability Analysis and Optimization of Test Method

Landslides ◽  
2000 ◽  
Vol 37 (1) ◽  
pp. 35-43_1 ◽  
Author(s):  
Masafumi OKAWARA ◽  
Toshiyuki MITACHI ◽  
Kenichi ONODERA
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Direct Shear Test ◽  
Shear Test ◽  
Slope Stability Analysis ◽  
Test Method ◽  
Direct Shear ◽  
Test Apparatus ◽  
Strength Parameters ◽  
Landslide Slope

scholarly journals Modifying Soil Shear Strength Parameters Using Additives in Laboratory Condition

2015 ◽  
Vol 10 (Special-Issue1) ◽  
pp. 120-130 ◽  
Author(s):  
Marjan Sadrjamali ◽  
Seyed Athar ◽  
Alireza Negahdar
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Slope Stability Analysis ◽  
Nano Particles ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Nano Silica ◽  
Strength Parameters ◽  
Soil Shear Strength

Mechanical and chemical processes and/or reinforcing materials are used in order to increase soil shear strength. Necessity for reinforcing and strengthening of soil in geotechnical and civil engineering projects requires use of new materials and reinforces. In recent years, although researchers have used new chemical compounds, however, nano-particles have not found their suitable situation. In this study, we have tried to increase soil shear strength parameters using different additives. Clay minerals are considered as problematic soils due to their engineering features. So, it is essential to reclaim them. In this research, clay with low plasticity property has been studied. Soil shear strength is an important factor for any analysis associated with stability including slope stability analysis. Slope stability analysis is used in earth dams and trenches. In this study, we have tried to increase soil shear strength parameters, i.e. cohesion coefficient (C) and internal friction angle (φ) using different additives. Direct shear test has been used for obtaining shear strength parameters as well as Mohr-Coulomb theory has been utilized for calculating of them. Although direct shear machine has its defects and its accuracy is low in comparison with tri-axial machine, however in this study it has been selected due to its simplicity and cheapness. Since this investigation aims to compare various additives and all tests have been done at same condition by direct shear machine, its deficiencies have been neglected. Additives used in present research include: Nano-silica in various percentage, Micro-silica, cement, lime (Cao) and these materials’ combination with together. The reason to choose Nano-silica is that it is a very active super-pozzolanic additive. This additive increases strength of sample significantly through chemical actions. Using silica in soil stabilization depends on type and size of silica particles so that the more finely the more continuous gradation, so property of being finer leads to decrease pores among particles and results to increase strength while light gradation has been achieved. Silica is one of the most popular materials which play a significant role in cohesion and filling. Results of experiments have shown significant effect of these additives in increase of soil shear strength parameters. The lime leads to modify behavioral features of fine-grained soils containing clay (properties such as swelling, shear strength, water absorption ability and plasticity properties) but it should not be in vicinity of sulphate ions.Since, in this condition, presence of lime not only doesn’t play an effective role but also it results to decrease in strength as well as increase in swelling. With regard to this reason, Calcium sulfate (gypsum) was added to soils containing lime in order to study swelling of soils stabilized with lime and nano-silica. Nano-silica increases Soil shear strength parameters while it is efficient in increasing of soil swelling, too.

Discussion of “Direct-Shear Test for Effective-Strength Parameters”

1963 ◽  
Vol 89 (1) ◽  
pp. 313-317
Author(s):  
Leslie G. Bromwell ◽  
Charles C. Ladd ◽  
Raymond H. Rogers ◽  
Carl B. Crawford
Keyword(s):  
Direct Shear Test ◽  
Shear Test ◽  
Direct Shear ◽  
Strength Parameters ◽  
Effective Strength

The Effect of Scale Direct Shear Test on the Strength Parameters of Clayey Sand in Isfahan City, Iran

2010 ◽  
Vol 10 (18) ◽  
pp. 2027-2033 ◽  
Author(s):  
R. Dadkhah ◽  
M. Ghafoori ◽  
R. Ajalloeian ◽  
G.R. Lashkaripo
Keyword(s):  
Direct Shear Test ◽  
Shear Test ◽  
Direct Shear ◽  
Strength Parameters ◽  
Clayey Sand

scholarly journals Determining the Shear Strength Properties of a Soil-geogrid Interface Using a Large-scale Direct Shear Test Apparatus

2020 ◽  
Author(s):  
Jakub Stacho ◽  
Monika Sulovska ◽  
Ivan Slavik
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Strength Properties ◽  
Coarse Grained ◽  
Direct Shear ◽  
Test Apparatus ◽  
Fine Gravel

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.

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