Seepage-stress-cracking analysis of concrete lining under high internal pressure

The issue of internal water leakage induced by concrete lining cracking under high internal pressure is a frequent challenge in the operation of pressure tunnels. This paper develops a novel seepage-stress-cracking analysis method of concrete lining under high internal pressure. It incorporates the cohesive element to model the discontinuous propagation of cracks within the lining. Additionally, the built-in contact simulation in the software ABAQUS is improved to represent the interface between the lining and surrounding rock. Furthermore, the model is validated by comparison with physical model experiment and engineering monitoring data. Finally, compared with the results of the traditional continuum method, a systematic analysis of the characteristics of the continuum/discontinuous analysis methods is carried out. The results indicate that under high internal pressure, cracking in the concrete lining is inevitable, and the distribution of cracks is characterized by being sparse and infrequent. Once stable seepage channels form at the cracks, the pressure difference between the inner and outer walls of the lining rapidly decreases, with the surrounding rock becoming the main bearer of the hydraulic load. The steel reinforcement stress exhibits a progression of slowly increasing, rapidly rising, sharply descending, and then maintaining a low value throughout the loading process. The overall trends from the continuous analysis model and the discontinuous analysis method are consistent; however, when precise description of the crack propagation process is required, the seepage-stress-cracking discontinuous analysis method must be used, as the continuous medium analysis method cannot simulate these characteristics.