A block-discrete-spring model based on deformable discrete element method is established; this model would be applied to simulate the rock failure process. In this model

the theoretical basis is continuum mechanics and block element is divided into discrete spring system with specific physical meaning. The stiffness of the spring can be obtained from the energy functional. In this way

element deformation and stress would be calculated by spring stiffness directly and efficiently. In the case of rock mass slope under gravity

the elastic result achieved with this model is the same as that of traditional finite element method. (FEM). On this basis

Mohr-Coulomb criterion with a tensile cutoff which used to judge the failure state and broken direction is proposed and implemented into the block-discrete-spring model. After the internal failure face established

the element will be divided into two elements by means of cutting block; and double judgement including element boundary and element interior is adopted to realize the crack initiation and propagation

which could mitigate the effect of initial mesh. Finally

the rationality of the failure result calculated by block-discrete-spring model is approved by some cases including split test with flattened disk

uniaxial compression and three point bending. The results show that this method can well simulate the crack initiation and propagation under tensile

compressive and shear conditions

by which the rock failure process can be realized from continuum to discontinuum.