| With the rapidly development of high grade highway construction, the number of highway tunnel is increasing, but in general, which can be divided into three categories:the multiple-arch tunnel, small interval tunnel and separate tunnel. Separate tunnel is one of the most common tunnel types, but during separate tunnel construction we often encounter many bad geological problems like bias-pressure, shallow-depth, water-rich and so on. These bad geological phenomenons often tend to appear in the tunnel entrance area, which will cause a lot of trouble and disasters to successful construction of the tunnel. Therefore, it will have high practical value and meaning in researching such special tunnel. This paper takes the Da-guang highway Jiulian-mountain tunnel for example, to proceed the numerical simulation and monitor measuring technology research of the large span bias in the shallow tunnel entrance section. The main content as follows:(1)Use finite difference FLAC3D software to analysis excavation of deformation and stress distribution in the process of the tunnel on the simulation and then find out the key parts of the settlement and deformation of the tunnel, and guiding the tunnel construction and supporting design.(2)Research some diseases encountered in the process of the tunnel construction, and analyze the reasons of diseases, then put forward some solving measures.(3)Use monitor measuring technology to master the situation of surrounding rock dynamic, adjust to supporting parameters, and play timely support role in the process of tunnel entrance construction.(4) Predict the surrounding rock eventually deformation and the steady state time according to the monitoring data by using the gray system theory.By practice, it proves that the result of this paper is to improve the safety, economy and rationality of tunnel in the process of construction, which has high practical value and can offer reference for similar engineering. |
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