Study On Deformation Law Of Upper Tunnel Caused By Freezing And Thawing

With the rapid development of urban subway construction, more and more underground transport lines turn up. Due to the lag planning and the existence of existing structures, the cross lines have to do construction across. Nowadays, the freezing construction has become the most reliable way in shallow tunnel crossing construction. However, the phenomena of frost heave and thawing settlement inevitably result in deformation or even destruction of the existing structures. In Panlongcheng Station to Hongtu Avenue Station interval of Wuhan Metro airport line, 6# contact channel beneath 3# line would be constructed by freezing method. This project belong the construction of long-distance contact channel beneath the existing tunnels closely. The study made through research based on this project by theoretical study, numerical simulation and physical model test.First of all, the classic two-dimensional stochastic medium theory was extended to space and the formula of displacement at any upper position caused by micro unit excavation was deduced. On this basis, three-dimensional computational models of frost heave and thawing settlement were set up. Then, the three-dimensional computational model established above was applied to project. By analyzing the results of the calculation, the frost heave and thawing settlement displacement variations of the upper stratum where 3# line tunnels exist were obtained.Secondly, the numerical model of the project was established by ANSYS. Through typical parameters research, the freezing construction of 6# contact channel was simulated. The frost heave and thawing settlement displacement variations of the upper 3# line tunnels were obtained by analyzing the results. Then, univariate study of frost heave displacement was also conducted.Thirdly, based on the similarity theory, simulated design was conducted for the project, and physics simulation was implemented in the laboratory.Finally, the conclusions obtained by theoretical calculations, numerical simulation and physics simulation were compared with each other. The research results were summarized and prospects of follow-up work were put forward.