The virtual multi-dimensional internal bonds(VMIB) is a multiscale mechanics model developed from the virtual internal bond(VIB). VIB considers solid material to consist of randomized ‘material particles’ in microscopic. The material particles are connected with virtual internal bond. The macro constitutive relation is derived from a given cohesive law between material particles. Different from VIB

a shear effect is introduced into the interaction between material particles in VMIB and the macro constitutive relation is derived in terms of bond stiffness. Owing to accounting for the shear effect

VMIB can present the diversity of Poisson ratio. According to VMIB

the macro response of material results from the micro bond evolution. The mechanical resistance of rock material subjected to confining pressure is considerably strengthened and the failure under such conditions is usually of the shear kind. The underlying micro mechanism of these macro presentation is that the evolution of bond stiffness is governed by the normal and shear deformation of bond itself while the evolution velocity is subjected to the stress state of the microelement at the continuous level. To describe this micro evolution mechanism of bond

a phenomenological evolution function of bond is proposed. By this evolution function

the fractures of brittle materials subjected to confining pressure can be simulated. However

as a tentative application

the presented method couldn’t represent the plastic flow phase in the complete stress-strain relationship since the plastic deformation is not accounted.