Research on Shear Strength Behavior of Slide Zone Soil in Ring Shear Tests

Taking slide zone soil of Huangtupo landslide as the object of study,the shear strength characteristics of sliding soil with nature water contents under different normal stress and shear rate was researched by using ring shear apparatus. The test results show that: peak shear strength and residual shear strength of slide zone soil both are along with increment of normal stress,and show strong linear relationship; shear rate between 0. 1 and10 mm /min has no obvious effects on residual shear strength,variation within ± 6%,while with shear rate becoming faster,more deformation is needed to reach the residual strength; with the increase of shear rate,residual cohesion decreases,residual inner friction angle gradually increases,peak shear strength and peak cohesion and inner friction angle all increase; shear rate has significant influence on softening characteristics of slide zone soil,and larger shear rate will result in more clay and pore water flowing away along the shear box side wall,so during drained shear test of sliding soil,a lower shear rate is very appropriate to obtain residual shear strength.