Direct Shear Test of Silty Clay Based on Corrected Calculating Model

Abstract

Direct shear test is one of the common method to study the parameters of shear strength and shear strength of soil. However, the current standard of geotechnical test method does not consider the calculation error caused by the change of shear area during shear process. In this paper, the direct shear test corrected calculation model considering effective shear area is established. This model shows that the test values of shear stress and normal stress are lower than the corrected values with the decrease of effective shear area, and the errors between them will increase with the increase of relative shear displacement. The analysis of the direct shear test results of silty clay shows that the errors between the test and corrected shear stress values are also related to the normal stress. The errors will increase with the increase of the normal stress. The shear strength parameters after correction tends to decrease. The effect of the corrected model on the cohesion is more significant than internal friction angle, and the effect on internal friction angle can be neglected approximately. On the basis of Mohr-Coulomb criterion, a shear strength criterion based on the corrected calculation model is established, which can be used to calculate the true shear strength parameters more accurately.