考虑盲管排水和防水板隔水的隧道支护体系分担水荷载解析解

AN ANALYTICAL SOLUTION OF WATER LOADING ON TUNNEL SUPPORTING SYSTEM WITH DRAINAGE OF BLIND TUBE AND ISOLATION EFFECT OF WATERPROOF BOARD

盲管排水和防水板隔水是富水区山岭隧道修建过程中的关键科学问题。研究围岩、注浆圈、盲管、防水板、初期支护以及二次衬砌共同承担水荷载相互作用,推导出基于盲管限量排水和防水板隔水效应的支护体系水荷载非线性解析式。引入盲管"导水系数"的概念,获得盲管和防水板是否正常工作,以及支护体系水荷载相互作用定量化关系,为排水量的"主动控制"提供依据。当盲管排水量增大时,初期支护、注浆圈和围岩承担的水荷载增大,二次衬砌水压力减小。以我国高速铁路祁连山大断面隧道为例,提出防水板隔水条件下,盲管排水量与衬砌外水压力、折减系数关系,实现盲管"主动排水",符合工程支护体系实际情况。提出合理的注浆圈厚度和渗透系数;随着水压力的增加,衬砌结构最不利位置由拱部向仰拱转移;墙脚压剪破坏、仰拱压弯破坏;确定衬砌结构极限承载力。研究成果可为富水隧道设计和施工提供依据。

The drainage of blind tube and isolation effect of waterproof board are two key scientific problems for tunnels in water-bearing stratum during construction. Analytical formula was derived based on drainage of blind tube and isolation effect of waterproof board. It involves the seepage field and water pressure ratio of support systems by considering the drainage of blind tube and isolation effect of waterproof board. The concept of blind tube hydraulic conductivity is introduced. The interactions among drain discharge,waterproof board and supporting system are obtained quantitatively. It can be applied for active control of drainage with blind pipe. The law of bearing water load of supporting system is studied under condition of different hydraulic conductivities of blind tube. In terms of Qilianshan tunnel on high-speed railway,the relationships are determined among drainage with blind pipe,external water pressure of lining and reduction factors. It could implement active drainage with blind pipe and accord with actual situation. Rational thickness and permeability coefficients of grouting reinforced region are put forward. With increasing water pressure,unfavorable position of lining transfers from arch to invert. Shearing-compression failure appears at wall-footing. Flexural failure takes place at invert as well. The ultimate bearing capacity of lining has been determined. Not only is it fit for deep tunnel in water-bearing stratum,but can be as reference for similar engineering.