Abstract：It is of great significance to study the coalescence mechanism of splitting failure of rock masses with intermittent joints under compression. On the basis of the crack isolating theory combined with the near crack line analysis method，the exact elastic stress field near the crack line is analyzed. The relation between the length of plastic zone along the crack line and external load is established by the matching condition of the elastoplastic fields on the boundary. The coalescence stress and the strength properties of rock masses are determined. The solution is a function of the geometry of the crack array. The results show that the coalescence stress and the strength of crack–weakened rock masses depend on the friction coefficient of crack interface，sliding crack spacing，orientation of cracks，and the half-length of crack. Experimental validations are given to illustrate the applicability of the proposed model.
