衬砌背后空洞条件下隧道结构受力特性研究

Massive tunnel detection data shows that there are lots of cavities behind the lining of the operation tunnel. Cavities behind the lining result in interaction relationship variation between surrounding rock and lining, which bring a huge security risk to the traffic and pedestrians in the tunnel. The subject of tunnel structure mechanical characteristics under the conditions of cavities behind the lining will be deeply studied based on the methods such as literature and field research, theoretical formula deduction and similarity model test. The main research contents are as follows: (1)The detection data base of cavities behind the lining in operational tunnel is established, and the general law of cavity morphology behind the lining are deeply mined; (2) Using conformal transformation, analytical solutions of secondary stress state and third stress state in surrounding rock, and analytical solutions of the stress state and the displacement state in linings are established based on planar elastic complex function theory. (3) Mechanical characteristics, deformation laws and failure modes of both tunnel surrounding rock structure and lining structure are studied by similar model test under the conditions of cavities behind the lining. (4) Health Criterion of tunnel structure under the conditions of cavities behind the lining is established based on the theory and model test research results.

大量的隧道检测数据表明，衬砌背后空洞广泛存在于运营隧道之中。衬砌背后空洞导致围岩与衬砌之间的相互作用关系发生变异，给隧道内的行车和行人带来了巨大的安全隐患。采用文献与现场调研、理论公式推导和相似模型试验等研究方法对衬砌背后空洞条件下隧道结构受力特性进行深入研究，主要研究内容包括（1）建立运营隧道衬砌衬砌背后空洞检测数据库，深层挖掘衬砌背后空洞形态的一般规律；（2）基于平面弹性复变函数理论，利用保角变换，建立衬砌背后空洞条件下非圆断面隧道围岩二次应力状态、三次应力状态以及衬砌应力状态、位移状态的解析解；（3）通过相似模型试验研究衬砌背后空洞条件下隧道围岩结构与衬砌结构受力特性、变形规律和破坏模式；（4）根据理论及模型试验结果构建衬砌背后空洞条件下隧道结构健康判据。

衬砌背后空洞导致围岩与衬砌之间的相互作用关系发生变异，给隧道内的行车和行人带来了巨大的安全隐患，因此，有必要对衬砌背后空洞条件下隧道结构受力特性这一课题进行深入研究。本项目的主要研究工作和研究结论如下：.（1）从设计理念、施工质量控制和运营管理养护3个技术层面上总结了衬砌背后空洞的一般成因，并提出了相应的控制措施。.（2）对96座公路隧道和112座铁路隧道近2000处衬砌背后空洞进行统计分析，获取了空洞分布位置、所处围岩级别以及几何尺寸的一般规律，结果表明，衬砌背后空洞一般易出现在围岩较差的拱顶和拱腰区域，且相比其他位置空洞状况更为严重，并建议将空洞几何形态处理为高度较小的环形空洞。.（3）基于弹性力学和复变函数分别推导出了衬砌背后存在任一空洞条件下围岩结构的应力及位移状态理论计算公式。.（4）基于荷载-结构模型原理，按照力法求解超静定结构内力和位移，推导出了衬砌背后空洞条件下衬砌结构内力计算公式，并编制了衬砌背后空洞条件下的衬砌结构安全性解算程序。.（5）通过模型试验模拟了衬砌背后空洞条件下围岩结构及衬砌结构的受力特性，试验结果表明：.① 衬砌背后空洞的存在对空洞附近的围岩接触压力及围岩应力状态产生了较大的影响，接触压力在空洞两侧出现了明显的集中现象，围岩应力在空洞外侧有显著降低，空洞附近围岩位移明显增加。.② 衬砌背后空洞的存在对空洞附近的衬砌结构受力状态改变明显，降低了衬砌结构的整体安全性。.（6）建立了衬砌背后空洞条件下隧道结构健康判据，并依托桑洲岭隧道病害的整治改造工程，通过数值计算、现场监测及检测等技术手段对隧道治理前后的隧道结构安全性进行系统地研究。