A Semi-Analytical Model and Parameter Analysis of a Collaborative Drainage Scheme for a Deeply Buried Tunnel and Parallel Adit in Water-Rich Ground

Abstract

For a railway or highway tunnel under high water pressure during operation, various factors such as the design of the drainage system, material aging, and pipeline blockage must be considered for the tunnels to work with the parallel adit to drain and control the external water pressure on the tunnel lining. A simplified steady-state seepage model in a semi-infinite multi-connected domain for the tunnel and parallel adit was established and was solved iteratively using the complex variable method and the Schwartz alternating method. After verifying the numerical simulation, parametric analysis, orthogonal tests, and multivariate nonlinear regression were also carried out. Results show that the simplified theoretical model and its semi-analytical algorithm have a fast convergence speed, and the obtained regression formula is simple, which is suitable for calculation and parameter analysis. A scheme that primarily relies on the parallel adit for drainage would make the external water pressure of the lining facing the parallel adit side less than that of the opposite side. Therefore, to reduce pressure uniformly and meet the requirements of surrounding rock stability, the horizontal net distance between the parallel adit and the tunnel should be no less than the tunnel diameter. Drainage volume of the parallel adit is linearly negatively correlated with tunnel water pressure on the lining and has the most significant effect on pressure reduction. The influence of the vertical distance between the parallel adit and the tunnel on water pressure is small.

Deep Rock Mass Engineering: Excavation, Monitoring, and Control

“…W. Chen, D. Zhang, Q. Fang, X. Chen, and T. Xu [10], based on the MC strain-softening rock with non-relevant flow criteria, established a new finite strain program for circular tunnels. X. Luo, Y. Xiang, and C. Yu [11] proposed an analytical model to analyze the realistic drainage conditions in parallel tunnels during operation. The research provides a beneficial reference for the optimization of drainage in deeply buried tunnels.…”

Analytical Solutions of Steady a Seepage Field for Deep-Buried Tunnel with Grouting Ring Considering Anisotropic Flow

“…Guo et al [11] proposed an exact analytical solution of a seepage field for underwater multiple tunnel problems using the Schwartz alternating method combined with conformal mapping. Luo et al [12] established a simplified steady-state seepage model for a deep buried tunnel and parallel adit, and the model was solved iteratively using the complex variable method and the Schwartz alternating method. Ying et al [13] presented an analytical solution for the hydraulic head that considers the effects of the seabed thickness and lining layers using conformal mapping and the principle of superposition.…”