Based on strain control consolidated undrained triaxial tests

stress-strain relationship and strength characteristic of expansive mud-stone are investigated and analyzed. The results show that the stress-strain relationship appears strain softening

and joints in mud-stone are important factor that influences strength characteristic. Different failure modes have different stress-strain relationships. Furthermore

the results also show that the peak strength

residual strength and residual strength ratio change with variation of confining stress

and development of pore pressure has three stages. By controlling shear speed ratio of triaxial test

influences of shear speed ratio on the stress-strain relationships and strength characteristic are discussed.