Undrained shear behaviour of intact infilled joint soil with triaxial shear tests under high pressure and its influence factor analysis

Abstract : The unconsolidated and undrained triaxial test is carried out on the intact infilled joint soils exposed at some major hydropower station under high pressure whose confining pressure is between 5 and 30 MPa to simulate the undrained boundary condition generated by rapid construction in-situ, and the mechanical behaviour of the infilled joint soils is discussed with the variation of physical property for each sample. The experiment results and failure mode are mainly controlled by high confining pressure: all the stress-stain relationships belong to strain hardening type, besides the samples after failure are presented as waist drum, and plastic failure occurrs. Moreover, a large amount of particle crushing occurrs among the wet particles, it is considered as the prime reason for the trend line of strength envelope decreasing with the increased confining pressure. The test data show discreteness for the effect of variation of physical property, and the sensitivity analysis (partial correction coefficient) indicates that: confining pressure p and saturation degree Sr have a major effect on the initial elastic modulus and failure stress ss; the void ratio e and the particle size distribution (d60) have the minimal effect. In addition, the equation proposed according to the shear behaviour can be used to estimate the strength features (E0and ss) of the infilled joint soils preliminarily in practice.