Abstract: In order to study the rheological characteristics, based on indoor triaxial compression test, the stress relaxation characteristics of saturated sliding zone soil from Huangtupo landslide in the Three Gorges Reservoir are analyzed. The XRD and XRF tests are carried out to investigate the mineral composition and chemical composition. The GDS triaxial test equipment is used to carry out the stress relaxation test of saturated sliding zone soil so as to describe the stress relaxation characteristic under different confining pressures and different strain increments. The test results show that the stress relaxation of saturated sliding zone soil has a relationship with confining pressure, axial strain rate, axial strain increment and relaxation time. The peak strength parameters and residual strength parameters can be obtained by the stress relaxation curves. The amount of stress relaxation and residual stress ratio of sliding zone soil increase with increasing confining pressure when the axial strain is close to the failure strain(15%); but the ratio of stress relaxation decreases. The volumetric strain in constant axial strain phase of sliding zone soil is much larger than that in increasing axial strain phase. When the strain rate is very small (0.02mm/min), the stress relaxation occurs during loading.

Key words: sliding zone soil, triaxial compression test, stress relaxation, deviatoric stress, volumetric strain, relaxation time