Influence of asymmetric blockage of the drainage system of a deep-buried tunnel on water gushing

Asymmetric blockage of drainage systems occasionally occurs, which seriously threatens the safety of tunnel operation. Based on theoretical analysis, a calculation expression of tunnel water inflow involving clogging parameters was derived. Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem, and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression. Studies have demonstrated that with increasing drainage system blockage degree, the amount of water inflow in the non-blocked area slowly increases, and the total amount of water in the tunnel gradually decreases. The hydrodynamic pressure in the blocked area non-linearly decreased, and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased. When the drainage system was not blocked, the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value. When the drainage system was blocked, the theoretical water inflow was 10.5% higher than the measured value. The difference between the measured value and the theoretical value is small, which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.