Abstract:To study the law of crack propagation under blasting, further guidingthe blasting design of fractured rock mass, the deep rock triaxial dynamic and static load test system was used to load the concrete specimens with pre-cracks one by one to obtain compressive strength of the concrete specimens. The high-speed camera was used to take the whole process of crack initiation and expansion in the specimens, and compared with the loading curve. The vertical initial pressure wasobtained when crack initiation occured. The study indicatedthat within a certain range, the larger the confining pressure of the test piece, the greater the pressure required for the crack initiation will be; and the presence of the secondary crack will make the main crack end more easily to crack under the action of external force, and the influence on inner end of the main crack wasmore profound than that on the outer end. The magnitude of this influence wasrelated to the length of the secondary crack and the crack spacing. The smaller the confining pressure, the larger the crack angle will be. The larger the secondary crack length and the smaller the crack spacing, the more easily the end of the main crack startedto crack. It can be concluded that the existence of adjacent cracks rendersan effect on the stress intensity at the end of the crack, and the degree of influence wasrelated to the parameters related to the collinear crack.