Abstract：Virtual multi-dimensional internal bonds(VMIB) is a multiscale mechanical model developed from virtual internal bond(VIB). It is deemed that the material particles in microscopic are connected with virtual normal bond and shear bond or with normal bond possessing normal and shear stiffness. The macro-constitutive relation in terms of bond stiffness is derived from the interaction between material particles. Owing to its ability to present the diversity of Poisson ratio，VMIB can be applied to more extensive engineering materials. The heterogeneous material，e.g. rock，is composed of different components. The mechanical property varies with location. In order to model the heterogeneous material，thereafter，to simulate its fracture process，the heterogeneity is primarily incorporated into VMIB. The heterogeneous material is assumed to consist of unit cells in which the virtual bonds are spatially randomly distributed. To represent the heterogeneity，the mechanical property of unit cells is assumed to be randomly distributed，which leads to a heterogeneity property on the integrated material level. However，the bond stiffness in a certain unit cell is assumed to be uniform，which leads to a homogeneity property on the cell level. To examine the performance of the presented method，the fracture process of a specimen subjected to confining stress is simulated. In the case where the rock is treated as a homogeneous solid，a run-through shear fracture is observed and the trace of fracture is regular while in the case that the rock is treated as a heterogeneous solid. Many fractures are observed to simultaneously initiate randomly in different locations；and then propagate and finally coalesce. But the general trend is of shear failure. The simulation results show that the presented method could simulate the fracture processes of heterogeneous rocks and primarily reflect the effect of heterogeneity on the failure behaviors of heterogeneous rocks.
