The Safety Analysis Of Tunnel Surrounding Weak Rock-Supporting System And Its Engineering Application

The safety problems of tunnel surrounding weak rock—supporting system under complex geologic conditions are obvious, so its safety analysis and evaluation is very important to tunnel safety construction and management. There are many influencing factors of tunnel safety, and the safety analysis and evaluation need consider the synthetic effect of many factors. The crack control of concrete lining in high ground-stress and soft-rock large deformation tunnel is a very complex problem, and it needs to analyze and evaluate the crack cause of concrete lining in all sides. The analysis and forecast of tunnel stability in weak rock tunnel during construction process has important impact on smooth construction. To detect danger situation and send out danger situation forecast in good time are able to reduce the probability of fatal construction accident, and it may give some valuable reference to construction managers.The main research is as follows.Firstly, the coupling effect of temperature fields and stress fields is analyzed, and the governing differential equations for coupled problem of temperature fields and stress fields is given, and the approximately analytical solution is given by the integral method of Kantorovch. Then it is applied to Wushaoling tunnel, and it is shown that the coupling effect has impact on the crack of concrete lining.Secondly, the crack calculation of concrete lining in cold regions tunnels is analyzed, and it considers the effect of extemal loads and thermal stress, and the last calculation result is made up of the result from external loads and the result from thermal stress. The method of solution to circular arches on the elastic foundation is introduced to calculate the crack from external loads, and the method to calculate the temperature crack is introduced.Thirdly, to analyze the research method of tunnel stability by the data of measured displacement in tunnel excavation, the stability criterion of tunnel surrounding rock is given, considering these aspects such as the total deformation, deformation rate and deformation rate ratio. The fuzzy model of danger situation forecast in tunnel excavation is given, and it is programmed by Matalab language. The fuzzy model is applied to Xiamen undersea tunnel, and it is shown valuable. Fourthly, the comprehensive safety fuzzy evaluation work of weak surrounding rock tunnel is divided into three phases, and it includes tunnel excavation, tunnel work and tunnel backfire. The comprehensive safety fuzzy evaluation model is given in three phases for tunnel. The work of the model includes the establishment of factor aggregate and evaluation aggregate, the formation of subordinate function, and analysis of the weight coefficient. The evaluation model is applied to Wushaoling tunnel, and it is suitable for safety evaluation.