By direct shear test

strength behavior of rock mass containing discontinuous joints with different joint surface morphologies is researched. The extension process to the rock mass can be divided into 4 stages: before initial cracking stage

crack stable growth stage

unsteady growth stage and friction stage. According to the experimental phenomena and the shear deformation curve

initial cracking strength

critical strength

failure strength and residual strength are researched. With the same normal stress

the joint surface morphology is rougher

not only the failure strength is higher

but also the initial cracking strength

critical strength

and residual strength are higher. With different joint surface morphologies

the ratio of the initial cracking strength and failure strength is about 70%; the ratio of the critical strength and failure strength is about 90%; but the ratio of t initial cracking strength and failure strength is not stable

which is about 50%-90%. The experimental verification is provided to further study failure theory of rock mass containing discontinuous joints.