复合式衬砌结构中衬砌分担围岩压力比例的研究

Study of lining sharing surrounding rock pressure in composite lining structure

复合式衬砌结构中衬砌分担围岩压力的评价方法是隧道工程技术的重要研究课题之一。依托某新建铁路隧道工程,提出了一种基于监测位移反分析评价围岩和支护应力,进而计算初期支护和衬砌背后压力的方法。根据监测位移和衬砌施作时间,确定初期支护的已发生变形和剩余变形。通过有限元反分析求出与已发生变形和剩余变形相对应的围岩和支护应力,得到初期支护和衬砌背后压力。对比初期支护背后压力及衬砌背后压力的现场监测和反分析的计算结果,两者比较一致,说明了该方法的可行性。该新建隧道初期支护闭合95 d后施作衬砌,计算得到衬砌背后压力约0.04~0.06 MPa,衬砌分担围岩压力比例约13%~16%。研究成果对复合式衬砌结构的设计具有一定的参考意义。

The evaluation method of lining sharing surrounding rock pressure in composite lining structure is one of the important research objectives in tunnel engineering. In this paper, an evaluating method of lining sharing surrounding rock pressure based on back analysis of monitoring displacements is proposed. Using the monitoring displacements and the lining casting time, the residual deformations of initial support are first determined; and then by useing finite element back analysis, the stresses of surrounding rock and initial support can be obtained; therefore the both of pressures behind the initial support and the lining are calculated. In order to show the applicability of the proposed procedure, the comparison of the in-situ observed and calculated is carried out for a newly built railway tunnel in which the lining is casted after 95 days in the initial support is closed. The pressure behind the lining is calculated to be about 0.04-0.06 MPa; and the ratio of lining sharing surrounding rock pressure is about 13 %-16 %. The results show that the proposed method can be useful for the design of composite lining structures.