Rock failure is an important phenomenon associated with crack propagation and energy conversion. In this paper, the uniaxial compression test of basalt is performed and acoustic emission (AE) activity is monitored throughout the process. The fracture characteristics and evolution of an internal crack in basalt are analyzed in detail with the obtained experimental data. A parallel bonding model is proposed in this study to investigate the failure of basalt subjected to uniaxial compression. The microscopic properties of particles and bonds in the model are calibrated against the results of mechanical behavior measured through physical experiments. We investigated the crack types and statistics of crack number by using a fish program in Particle Flow Code (PFC) under uniaxial compression. Meanwhile, the discrete element computational model monitored the information of energy upon each bond breakage during the loading process. All the numerical and test results are presented in graphs and discussed in detail. The PFC can accurately reproduce the crack propagation, failure patterns and energy conversion of basalt on a microscopic scale, which may not be monitored in the actual test.

Deformation control and stability analysis are very important for tunnel construction. Large deformations of the constructed primary support accompanied by lining cracking and spalling occurred in the Dongxishan Tunnel located in Chaozhou City, northeastern Guangdong Province, China, posing a serious damage to the tunnel safety. In order to determine the causes of large deformations, comprehensive investigations have been performed by combining field monitoring, laboratory tests, and mechanism analyses. The results show that there have been three main factors resulting in the occurrence of large deformations in the Dongxishan Tunnel: the plastic flow of surrounding rock due to low strength of silty clay, obvious creep behavior, and water-weakening effect of silty clay. Besides, based on the preceding mechanism analyses of large deformations, many countermeasures were proposed during construction, including double row pipe pregrouting reinforcement, strengthening primary support, and timely closing of temporary support. These countermeasures can effectively deal with large deformation problems in the Dongxishan Tunnel from the in situ feedbacks. This paper can provide useful guidance for avoiding the similar anomalies in the following excavation and support of Dongxishan Tunnel.