The hydromechanical behavior of deep intact Beishan granite is investigated with MTS815 rock mechanics test system. With the help of 3D acoustic monitoring system, a special attention is paid on the damage evolution process and its impact on the permeability of rock sample during triaxial compression test. The experimental results indicated that the damage evolution has a significant influence on the permeability variation of granite. Under the same confining pressure, a good accordance between the damage and permeability evolution tendency is noticed, which can be divided into three phases.
As the last barrier of the multi-barriers system, the surrounding rock plays a critical role to ensure the stability and safety of the repository project. The initiation and propagation of the excavation damaged zone may not only lead to the degradation of the mechanical properties of host rock, moreover itmay serve as the potential passage of nuclide migration. Therefore, the damage evolution and its impact to permeability of rock mass is of wide interest in the physical-mechanical investigation of the host rock, particularly to the brittle rock like granite in which the microcracks don't have the self-sealing capacity.
In last decades, the permeability properties of damaged rock have been extensively investigated. The permeability variation of damaged granite during triaxial loading process is studied by Souley et al. and Oda et al. The degradation of permeability induced by the initiation and propagation of cracks are also reported by Suzuki et al. and Schulze et al. It is revealed that, as a consequence of the appearance and growth of cracks, the permeability of rock mass can be significantly increased, particularly in the post-peak region. Based on the experimental results, some relationships between the permeability and mechanical behavior are also established. However, the works carried out mainly concentrated on the impact of macroscopic behavior of rock sample, like deformation and stress condition. Few attentions have been paid on the damage evolution process, which is actually the essential mechanism responsible to the permeability changes.