An experimental study on shear strength behavior of soils under low confining pressure

Abstract

Mechanical behavior of soils is highly dependent on their composition. In order to gain better understanding of change in strength parameters according to soil composition, direct shear tests were conducted in this study. Sand was selected as preliminary soil type. Fine grained soil was mixed with sand step by step. Amount of fine grains was increased 10% in each step. Eleven different mixtures were obtained and standard proctor tests were conducted to determine highest unit weight and optimum water content for each mixture. Then, direct shear tests were conducted for each mixture. Four different confining pressures were chosen, and confining pressures were 9.81 kPa, 19.62 kPa, 40.81 kPa and 58.86 kPa. Shearing rate was chosen as 0.25 mm/min for sandy soils. When the tests were conducted for fine grained soils, shearing rate was chosen as 0.065 mm/min. Results of this study might help understanding of failure of soil under low confinement.