The initiation, propagation, coalescence and failure mode of brittle jointed rock mass influenced by fissure water pressure have always been studied as a hot issue in the society of rock mechanics and engineering. In order to analyze the damage evolution process of jointed rock mass under fracture water pressure, a novel numerical model on the basis of secondary development in fast Lagrangian analysis of continua (FLAC3D) is proposed to simulate the fracture development of jointed rock mass under fracture water pressure. To validate the feasibility of this numerical model, the failure process of a numerical specimen under uniaxial compression containing pre-existing fissures is simulated and compared with the results obtained from the lab experiments, and they are found to be in good agreement. Meanwhile, the propagation of cracks, variations of stress and strain, peak strength and crack initiation principles are further analyzed. It is concluded that the fissure water has a significant reducing effect on the strength and stability of the jointed rock mass.

The initiation, propagation, coalescence evolution behaviors of cracks in rock mass, and even fissure water pressure have significant impacts on the strength and stability of fractured rock mass in engineering projects. In this paper, we propose an elasto-brittle constitutive model considering fissure water pressure based on the computer code three-dimensional fast Lagrangian analysis of continua (FLAC^3D). This constitutive model is initially validated through a pre-cracked rock-like-material specimen in the laboratory experiments and then proved to actually simulate the initiation, propagation, and coalescence characteristics of cracks considering fissure water pressure in brittle fractured rock mass. Afterwards, it is used to investigate the stability of the right bank slope in Dagangshan hydropower station which is located in Sichuan province, China. The whole stability of this rock slope during construction has been simulated using the above constitutive model. The development principles of cracks in a selected area and the displacement field of the slope under different fissure water pressures are obtained in the process of excavations. It is concluded that fissure water pressure has obvious and significant effect on the strength and stability of fractured rock mass.