降雨作用下浅埋隧道松散围岩塌方机制

摘要

In order to reveal collapse mechanism in loose wall rock of shallow tunnel under rainfall,the cusp-catastrophic model is established based on catastrophe theory.Considering the case that surrounding rock of shallow tunnel is combined with different rock and soil mass,the instability criterions are derived when surrounding rock is combined with double strain-softening mediums or with single strain-hardening layer and strain-softening layer.The main influence factors and mechanism of collapse are analyzed.Then,the viewpoint is put forward that collapse of shallow tunnel can be predicted by data of ground settlement based on the catastrophe theory.It＇s feasibility and reasonability is tested by the collapse that occurs in construction of Maanshan tunnel.The results show that the derived instability criterions can analyze the collapse mechanism effectively.It is more feasible and tally with the actual that the data of ground settlement is used to predict the collapse in loose wall rock of shallow tunnel.%为揭示降雨作用下浅埋隧道松散围岩塌方机制,基于突变理论,建立浅埋隧道塌方的尖点突变模型.考虑不同本构关系的隧道围岩组合,分别推导双层应变软化介质、单层应变硬化介质及应变软化介质组合的围岩失稳力学判据,分析诱发塌方的主要影响因素,揭示雨水入渗作用下浅埋隧道塌方机理.以马鞍山隧道为工程案例,运用地表沉降监测数据进行浅埋隧道塌方突变预测.研究表明,浅埋隧道塌方力学判据可有效用于塌方机制分析,用地表沉降数据预测浅埋隧道松散围岩塌方更为合理和符合实际.