Based On The Nmt Method For Underground Cavern Stability Numerical Analysis

With the rapid development of the national economy, the basic establishments of our country have already been making great achievements in the recent years. All kinds of section underground cavern have been applied more and more widely in the railway and road tunnel, the hydroelectric project powerhouses, the municipal project, military and defense project, underground business buildings and so on. However, we have been mainly adopting the method of qualitative analysis on the base of the New Austrian Tunneling Method theory for a long time, in the underground structure design, construction and the stability of surrounding rock. This can't keep up with the developing situation of the modern underground engineering yet. So, it is necessary to study a numerical calculation method in selecting support parameters etc. Meanwhile, we should learn from the successful experience of other advanced country's cavern construction actively.Firstly, the paper introduces the basic principles of the Norwegian Method of Tunneling in detail and compares it with the New Austrian Tunneling Method comprehensively. It points out that we can achieve better technological and economic results by the NMT, therefore the NMT is worthy of popularizing in the cavern construction. Secondly, the paper gives an overall summing-up to the design methods of the underground engineering support structure and explains the limits of each method. It also discusses the five kinds of surrounding rock stability's criterion and points out that it is impossible to establish a current quantitative stability criterion at the same time. Thirdly, a new method for the large section caverns is put forward to determine the primary supporting parameters of surrounding rock, which combines the NMT and numerical analysis of finite element method with the similar engineering analogy to determine the parameters. Finally, the stability of small, changed and large section underground cavern is numerically analyzed by plane strain elastic-plastic finite element method. Optimum study on three different excavations of underground opening is given at last.By the aid of the finite element software ANSYS, we acquire several significant results. Furthermore, the model and the analyses method provide an important theory base for the supporting structure design and construction of the cavern.