| With the implementation of the western development strategy and the western economy development, the western traffic construction achieve a new upsurge, a large number of loess highway tunnel has emerged. In order to study the deformation of the Loess Tunnel based on Dayoushan Loess tunnel belonging to the main route to State Road Dan'dong to Lasa Qing'hai Habitat of the highway. Using finite element software(MIDAS-GTS)make a simulation analysis about the construction of loess tunnel to study the law of deformation after excavation separately in the shall buried loess tunnel. Studies in different depth conditions, using different construction methods of rock deformation after the excavation, respectively study depth 20m and 40m conditions in the cross diaphragm, center diaphragm and annular excavation method three core leave the construction method of rock deformation, based on the surface deformation, vault settlement and peripheral convergence of comparative analysis of data and found the same depth excavation under the condition of core of circular cross in indigenous better leave next door, cross in hair method of better next method, and gives corresponding conditions recommended construction method.Combining the results of finite element simulation, and the results of monitoring measurement to calculates the tunnel excavation, and according to the actual displacement of various construction procedures of total displacement of the total displacement ratio relationship, summarizes the key process of construction, the surrounding rock deformation for construction to provide the scientific basis and guidance of construction safety, ensure the safety of the construction.According to the collapsible loess, and in the new and old loess junction easily uneven settlement after using finite element analysis software, a preliminary analysis of the foundation, after reinforcement in three conditions of vaults settlement and arch sedimentation upward.
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