A method for determination of ϕb for statically compacted soils

1996 ◽  
Vol 33 (2) ◽  
pp. 272-280 ◽  
Author(s):  
S Y Oloo ◽  
D G Fredlund
Keyword(s):  
Shear Strength ◽  
Unsaturated Soils ◽  
Direct Shear Test ◽  
Shear Test ◽  
Strength Parameter ◽  
Direct Shear ◽  
Compacted Soils ◽  
Shear Strength Parameter ◽  
Direct Shear Apparatus

The unsaturated shear strength parameter, ϕb, is usually determined using triaxial of direct shear apparatus that have been modified to allow for the control and (or) measurement of pore-air and pore-water pressures. A fairly high level of expertise is required for the characterization of ϕb using these modified apparatus. A simple procedure for determining ϕb for statically compacted soils at different water contents is presented along with a method of analysis. The tests can be performed on a conventional direct shear apparatus. The unsaturated shear strength parameter, ϕb, obtained using the proposed procedure is shown to be comparable to that obtained using the modified direct shear test. Since the proposed procedure utilizes standard laboratory direct shear equipment and takes a relatively short time to complete, it offers an easy and convenient alternative for the determination of ϕb for statically compacted soils. Key words: shear strength, matric suction, unsaturated soils, statically compacted soils, direct shear test.

Determination of the shear strength of unsaturated soils using the multistage direct shear test

2011 ◽  
Vol 122 (3-4) ◽  
pp. 272-280 ◽  
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Shear Strength ◽  
Unsaturated Soils ◽  
Direct Shear Test ◽  
Shear Test ◽  
Direct Shear

Determination of the shear strength parameters of an unsaturated soil using the direct shear test

1988 ◽  
Vol 25 (3) ◽  
pp. 500-510 ◽  
Author(s):  
J. K. M. Gan ◽  
D. G. Fredlund ◽  
H. Rahardjo
Keyword(s):  
Shear Strength ◽  
Unsaturated Soils ◽  
Testing Procedure ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Wide Range ◽  
Practical Engineering ◽  
Direct Shear Apparatus

Multistage direct shear tests have been performed on saturated and unsaturated specimens of a compacted glacial till. A conventional direct shear apparatus was modified in order to use the axis-translation technique for direct shear tests on unsaturated soils. The soil can be subjected to a wide range of matric suctions. The testing procedure and some typical results are presented. Nonlinearity in the failure envelope with respect to matric suction was observed. Suggestions are made as to how best to handle the nonlinearity from a practical engineering standpoint. Key words: shear strength, unsaturated soils, negative pore-water pressures, soil suction, direct shear.

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

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.

scholarly journals Studi Eksperimen Pengaruh Penambahan Serabut Kelapa Terhadap Kohesi dan Sudut Geser Tanah Lempung

2021 ◽  
Vol 3 (2) ◽  
pp. 256-259
Author(s):  
Pebrinar Sangle
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Direct Shear Test ◽  
Shear Test ◽  
Clay Soil ◽  
Dry Weight ◽  
Strength Parameter ◽  
Direct Shear ◽  
Before And After ◽  
Coconut Fibers

This research is intended to study the shear strength of clay soil before and after adding coconut fibers. Shear strength is one of the factors that are taken into account to find the bearing capacity of the soil. Soil stability is a way to improve or change the nature of an unfavorable subgrade condition to be better in terms of the bearing capacity of the subgrade for the construction to be built on its Strength parameter testing shear using direct shear test equipment with total stress conditions. This research used coconut fiber variations of 0%, 1%, 2%, 3%, and 4% of the dry weight of the soil. The results of the direct shear test showed an increase in the value of soil cohesion (c) and shear angle (φ). This shows that the addition of coconut fibers to clay soil can increase the value of shear strength.

scholarly journals Determination of Residual Shear Strength from Reversal Direct Shear test: Analysis and Recommendation

2020 ◽  
Vol 8 (5) ◽  
pp. 5053-5058
Keyword(s):  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Slope Failure ◽  
Failure Zone ◽  
Direct Shear ◽  
Residual Shear Strength ◽  
Test Analysis ◽  
Undisturbed Sample

Reversal Direct Shear test is used for the determination of residual shear strength of soil sample. This test was conducted on undisturbed and remolded sample of embankment slope of Pa Bon Dam, Thailand that had failed after operating for 10 years. The undisturbed sample was taken from the downstream slope (non-failure zone) while the remolded sample was taken from the upstream slope (failure zone). The results yielded identical values of residual strength parameters. On the basis of laboratory test, various recommendations are proposed for the conduction of this test in future.

The Improved Shear Strength Calculation Method in Direct Shear Test

2013 ◽  
Vol 405-408 ◽  
pp. 353-357
Author(s):  
Yun Dong ◽  
Yong Cun Wang ◽  
Li Guo Lu ◽  
Wei Wang
Keyword(s):  
Shear Strength ◽  
Calculation Method ◽  
Direct Shear Test ◽  
Shear Test ◽  
Simple Structure ◽  
Strength Calculation ◽  
Direct Shear ◽  
Specific Material ◽  
Direct Shear Apparatus ◽  
Test Result

Direct shear test is broadly used to get the strength of soil, joints, and specific material in the field of geotechnical engineering because its simple structure and easier operation. But the current direct shear strength calculation does not concern on the variation of the shearing surface during the test, has no regard for the effects of the shearing area on the shear strength, so the test result is not the really strength of the samples. To discovery the affection of the shearing surface on the direct shear strength, three different calculation methods of shear surface and its affection on the shear strength were put forward based on the new mathematical model and large number of experimental with improvement direct shear apparatus, the new calculation method makes the result more accuracy and closer to the really shear strength of the samples.

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

Soil Shear Strength Characteristic in Slope Disintegration Area

2013 ◽  
Vol 353-356 ◽  
pp. 735-739
Author(s):  
Xiao Ming Zhang ◽  
Shu Wen Ding ◽  
Shuang Xi Li
Keyword(s):  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Clay Content ◽  
Scientific Basis ◽  
Soil Mechanic ◽  
Direct Shear ◽  
Soil Cohesion ◽  
Soil Shear Strength ◽  
The Relationship

Development of slope disintegration is close to soil mechanic characteristics such as shear strength indices. Soil grain diameter and water content were tested. Soil direct shear test was conducted to analyze the relationship between shear strength indices and the influencing factors. The experimental data indicate that clay content and the range affect soil cohesion value and the scope. Soil cohesion increases with bulk density before 1.6g/cm3. But it decreases when the bulk after that. The results could provide a scientific basis for control of slope disintegration.

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