Abstract:

To research the mechanical properties of soil in the sliding zone of rainfall induced landslide, we investigated the stress strain relation, shear strength index and initial deformation modulus by triaxial shear tests. The results indicated that the water content has remarkable impact on the development mode of stress strain relations. When the water content is smaller than the plastic limit, the stress strain relation experienced a process from elastic deformation to strain hardening, to peak value emergence, then to strain softening, and finally to shear failure surface; while when the water content is larger than the plastic limit, the mode of strain stress relations generally developed from strain hardening swell at strength decreases, which can be divided into three phases: when the water content is smaller than the plastic limit, the variation of shear strength is not obvious; when the plastic limit is 17% (in the vicinity of the average value of liquid limit and plastic limit), the shear strength reduces most rapidly; and afterwards, the decrease of shear strength slows down. With the increase of water content, the cohesion decreases in an approximate bilinear relation.

Key words: sliding zone soil, water content, stress strain relation, failure mode, strength index.