Model test and numerical simulation research of water leakage in operating tunnels passing through intersecting faults

During operation of the Kaiyuansi Tunnel, water leakage from the lining frequently occurs in the rainy season, seriously impacting the safety of the tunnel structure. To study the occurrence mechanism and evolution law of water leakage in operating tunnels passing through intersecting faults under different burial depths, both a large-scale 3D physical model test and numerical simulations were carried out. The results of the water leakage volume, vertical displacement and hydraulic pressure of the monitoring sections in the physical and numerical models were analyzed. The vertical displacement and hydraulic pressure of the model increase with increasing applied load and water pressure. Because of the higher water conductivity and lower strength of the intersecting faults, the influence of intersecting faults on tunnel water leakage is greater than that of surrounding rock. The intersecting faults have a very close hydraulic connection, and the main fault plays a major role in the seepage of groundwater. The results show that the internal defects of the lining material and quality defects of the tunnel construction are the main factors leading to water leakage in operating tunnels, and the uneven settlement of strata is another important factor in lining cracking and water leakage of operating tunnels. Finally, some useful suggestions and conclusions for tunnel construction and operation were obtained from the test results.