水底隧道复合式衬砌水压力影响因素分析

Analysis on the Factors affecting Water Pressure upon Composite Lining of Underwater Tunnel

富水量较大的水底隧道,隧道防排水系统对于控制隧道涌水量和衬砌外水压力十分重要。采用数值计算方法,研究固定水头下水底隧道不同注浆参数、衬砌渗透系数及隧道控制排水量对衬砌水荷载的影响,并与轴对称解析解结果进行对比验证。研究结论:(1)渗透系数增加和注浆圈厚度减小都致使衬砌外水压力的增加;(2)初衬渗透性的变化对初衬外水压力的影响十分显著;(3)数值解与解析解的结果相差不大,非圆形隧道截面可利用等效半径求解衬砌外水压力和隧道涌水量的解析解,并用于隧道防排水的初步设计;(4)隧道注浆圈参数和初衬渗透系数一定时,增大控制排水量有利于减小二衬背后外水压力。

As to water-rich underwater tunnel, the tunnel waterproofing and drainage system is very important for controlling the tunnel＇s water inflow and the lining＇s external water pressure. Therefore, this paper, considering the underwater tunnel with constant water head, by using numerical calculation method, researched the influence on the lining＇s external water pressure caused by different grouting parameters, different lining permeability coefficients and different controlled water discharge; and then conducted relevant verification in comparison with the result of axisymmetrical analytic solution. The research come to the conclusions： （a） Either increasing the permeability coefficient or reducing the grouting circle＇s thickness, will all result in an increasing of the external water pressure upon the lining. （b） The change of permeability of initial lining has significant influence on the initial lining＇s external water pressure. （c） There is little difference between the two results of numerical calculation and analytic solution, so the lining＇s external water pressure result and the tunnel＇s water inflow result, both obtained from analytic solution by using equivalent radius technique, can be used for the tunnel with non-circular cross-section as well as can be used for the preliminary design of tunnel waterproofing and drainage. （d） When the grouting parameters and the permeability coefficient of initial lining are constant, increasing the controlled water discharge is beneficial to reducing the external water pressure behind the secondary lining.