Abstract: Using the RFPA numerical code, the failure process of vertically stratified rock mass around underground excavations is simulated and the failure characteristics between vertically stratified and intact rock mass are comparatively discussed under different lateral pressure coefficients. The results show that the lateral pressure coefficient has a significant influence on the failure mode of vertically stratified rock mass. Only if the lateral pressure coefficient is smaller than 1, would the side walls take the buckling failure mode; or else, the failure zones mainly concentrate at the crown and floor of tunnel. It is also found that the beam-slab theory in application to the structural mechanics does not entirely suit the stability evaluation of vertically stratified rock mass. Furthermore, it is found that for deep excavations the failure mode of rock mass is controlled mainly by the stress instead of structural planes. It is the stress that mainly controls the failure mode of rock mass, other than the structural plane in the rock mass.