Study on Strength Parameter Selection for Slope Stability Analysis of Red Clay (in Chenzhou) under Dry-Wet Cycling

To select proper strength parameters for slope stability analysis of red clay, study on the influence of dry-wet cycling and water content variation was performed based on direct shear tests. It is found that: (1) shear strength parameters are greatly affected by water content instead of cycling; (2) with the decrease of water content, shear strength increases, especially, relationship curve between cohesion and water content is concluded to be logarithmic; (3) under the same experimental conditions, cohesion and friction angle of hard plastic clay are generally larger than those of soft plastic clay. Dry-wet cycling leads to cracks which are harmful to slope integrity. Slope failure of red clay under dry-wet cycling, appearing to be shallow sliding, is resulted from cracks and water infiltration. Consequently, it can be analyzed with (c_u, φ_u) or (c_cu, φ_cu) of saturated upper layer, as well as taking cracks on potential sliding surfaces into consideration.