Influence of leakage under different joint locations on river-crossing tunnels: Experimental and numerical investigation

Joint leakage is one of the major defects in river-crossing tunnels during operation period. The influence of leakage under different joint locations on the tunnel structure is different. In this paper, a combination of model tests and numerical simulations was developed to investigate the influence of leakage under different joint locations during operation period on the tunnel structure and the strata. Specifically, the difference of joint permeability coefficients with different locations was considered, and the formula quantifying the relationship between the permeability coefficient and the angle of joint was established. Nanjing Dinghuaimen River-Crossing Tunnel in China was used as the engineering background to study the leakage patterns for different locations of joints. The results show that the tunnel structure responds more to leakage at tunnel arch bottom and foot during operation period. When leakage occurs at tunnel arch foot, the infiltration volume is 33.6% more than that at the tunnel vault, and the surface settlements are 2.4 times more than that at the tunnel vault. The surface settlement caused by the joints is related to the infiltration volume. The location of the joints affects the shape of the lining deformation and the overall deformation is less. The results of this paper have certain guiding significance for tunnel maintenance projects.