Total Strength of Saturated Clay and Earth Pressure in Excavation by Total Stress Analysis Method

Abstract:

Based on the review of the concept of total strength S_u and the principle of “ method”, it is pointed out that directly substituting the strength parameters of c_cu and φ_cu by triaxial consolidated undrained shear test, and the strength parameters of c_cq and φ_cq by direct shear test into Rankine’s earth pressure is a uncorrected analysis method. It results in the misleading of the application of the total stress analysis method. According to the principle of the two kinds of test, the formulations of total strength S_u using the strength parameters of c_cu,φ_cu, and c_cq,φ_cq are derived. Then, according to the principle of “ method”, correct earth pressure equations applied to unloading condition in excavation are presented. Based on the new equations, the analysis methods given in several domestic standards or specifications are discussed. Finally, different kinds of strength parameters in earth pressure analysis are evaluated with analysis examples.

Key words:saturated clay;total strength;total stress analysis;earth pressure