Abstract：The mechanical behavior of jointed rockmass is mainly controlled by joints. The interaction between joints and the coalescence of joints are important problem for geotechnical engineering. The coalescence of two collinear joints and a periodic row of collinear joints are investigated by using Dugdale-Barenblatt model，and the high level of compression-shear stress and interaction between joints are considered. The mechanical conditions of joint propagation are determined by stress intensity factor and the length of damage and strain localization zone. Experimental validations are given to illustrate the applicability of the proposed model. The conclusions are of important significance for rockmass engineering.
