Meso mechanical mechanisms of thick-walled hollow rock cylinder during failure process

At present, the conventional bonded particle model is difficult to represent the irregular structural feature of mineral grains in rock. A numerical model of thick-walled hollow cylinder of rock to reflect the feature of mineral grain in rock was established using the flat-joint contact model based upon the particle flow theory and PFC code. The failure mechanism and law of thick-walled hollow cylinder of rock with the different inner and external pressures were investigated from the meso mechanical viewpoint. When inner pressure was equal to zero, the microcracks were mainly tensile type in the failure process and the spalling fragmentation particles formed a V-shaped damage area symmetrical to the cylinder axis. When the inner pressure was not equal to zero, the limiting external pressure increased and the shear microcracks gradually dominated in the failure process with the increase of the inner pressures. Meanwhile, the symmetrical V-shaped damage area in the specimen receded and the failure expanded towards all the directions from the inner rock face. With or without the inner pressure, the variation of the failure parameters such as the external pressure and the external volume strain can be divided into three stages. © 2016, Science Press. All right reserved.