Abstract: The phenomenon of cavity behind the tunnel lining as one of the main diseases occurs in the construction and operation of road tunnel, which changes the interaction between tunnel lining and surrounding rock and induces the concentration even failure of tunnel structure. The physical model test was adopted, and three test cases were simulated: no cavity, one cavity and multiple cavities. By comparing the variation rule of surrounding rock pressure, lining axial force and bending moment under the action of overburden load, the following main conclusions are obtained: ①When there is no cavity behind the tunnel, the lining and the surrounding rock contact well, and the surrounding rock pressure, lining axial force and bending moment will increase with the increase of overburden load. ②When there are cavities behind tunnel lining, the surrounding rock pressure cant be passed to the lining structure in the range of cavities. In that way, the rock pressure, axial force and bending moment of lining will reduce with the increase of overburden load; but the lining structure is easy to crack because of the increase of eccentricity. ③The influence of the cavity behind the lining on the safety factor of the lining vault is the greatest, the more the number of cavities, the more obvious the reduction of the safety factor, but the distribution law of the safety factor in the tunnel cross-section has not been changed.

Key words: tunnel engineering, structural safety, model test, cavities behind lining, internal force of structure

摘要： 隧道衬砌背后空洞现象是隧道建设与运营中主要病害之一，这会改变隧道衬砌与围岩的相互作用关系，引起隧道结构应力集中而破坏。采用物理模型试验方法，模拟了隧道衬砌背后无空洞、单空洞、多空洞等3种工况。通过对比分析这3种工况在上覆荷载的作用下围岩压力、衬砌轴力及弯矩变化规律，获得了以下主要结论：①隧道无空洞时，衬砌与围岩接触良好，围岩压力、衬砌轴力及弯矩均随上覆荷载的增加而增大；②隧道衬砌背后存在空洞时，空洞范围内围岩压力无法传递到衬砌结构上，导致围岩压力、衬砌轴力及弯矩均随上覆荷载增加而减小，但衬砌结构因偏心距增大容易发生开裂破坏；③衬砌背后空洞对衬砌拱顶安全系数的影响最大，空洞数量越多安全系数降低越明显，但未改变安全系数在隧道横断面内的分布规律。

关键词: 隧道工程, 结构安全, 模型试验, 衬砌空洞, 结构内力