Drained Shear Strengths of Jingmen Compacted Expansive Soil

The long-term stability of clay slopes is mainly controlled by drained shear strengths.Drained shear strengths,including the peak,fully softened and residual shear strengths,are suitable for different conditions.The drained shear strengths of Jingmen compacted expansive soil are investigated experimentally.Drained direct shear tests on specimens reconstituted from slurry are performed to obtain fully softened shear strengths.Drained multiple reversal direct shear tests on compacted specimens are performed to obtain the peak and residual shear strengths.The effects of percent compaction,stress level,shear displacement on drained shear strengths and volume change behavior during shearing are investigated.The conclusions are drawn as follows:(1) The effective stress friction angle of peak shear strength is approximately equal to that of fully softened shear strength,which is about 20°.(2) The effective stress cohesion of peak shear strength is 18.4 kPa,and that of fully softened shear strength is zero.(3) The drained residual failure envelope is nonlinear,which can be perfectly described by the power function equation presented by Lade (2010).