Abstract
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.
Highlights
Shear strength of soils is one of the most critical parameters in the geotechnical designs used in analyzing problems such as lateral soil pressure, bearing capacity of foundations, slope stability, earth dams, and other geotechnical problems [1, 2]
Considering this fact, together with shear tests were conducted based on the Amer- application of four different sand and three difican Society for Testing and Materials (ASTM) ferent normal stresses of 60 kPa, 120 kPa, and standard (ASTM D3080) at a constant and low 180 kPa, more than 36 direct shear tests were displacement speed of 0.5 mm/min under three conducted
The present study was designed to determine the effect of D50s and particle size distributions on the deformation and shear strength characteristics of four sandy soils
Summary
Shear strength of soils is one of the most critical parameters in the geotechnical designs used in analyzing problems such as lateral soil pressure, bearing capacity of foundations, slope stability, earth dams, and other geotechnical problems [1, 2]. Simoni and Houlsby (2006) conducted 87 large direct shear tests on sand-gravel mixtures of different D50s and came to the conclusion that increasing D50 would increase the dilatancy rate and the critical state friction angle. The D50, on the other hand, has a more noticeable impact on shear strength than on relative density In another investigation, Hamidi et al (2012) [27] studied the shear strength and dilatancy of well-graded sand-gravel mixtures by conducting 27 large-scale direct shear tests and reported that the particle size distribution and D50 of the tested soils significantly affect their shear strength. In a comprehensive study of the impact of D50 on the shear behavior of soils, Rasti et al (2021) [28] performed a series of direct shear tests on four different sands and found that the D50 of soils affects their critical friction angle. The first part deals with materials and testing programs, the second part discusses the impact of D50 on the shear strength behavior of sands, while the last part discusses the deformation behavior of soils
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