The Study Of Deformation Mechanism Of The Tunnel DA-FENG-YA-KOU

The tunnel Dafengyakou is located in the sixth contract sect of the FreewayYUAN-MO line, linking the Yuanjiang County in Yuxi city with the Mojiang County in Simao territory. The tunnel is the longest highway tunnel of Yunnan Province among the building projects at present (the upper and lower lines total length 6727 meters). The tunnel DA-FENG-YA-KOU has special geographical position and complicated geological situation. The difficulty met and technological difficult problem are all rare in the whole country and even underground project in the world. The conditions in the upper line K254 +895-939 are even worse which contains faults and fragment zones as well as abundant groundwater.Based on foundational study of the engineering geologic and hydrogeologic conditions, the conditions of the country rock mass along the upper line K254+895- +939 are analyzed in detail in this article. At the same time, combined the result of the TSP for the country rock mass of the tunnel, the stability analysis and preliminary appraisal of the country rock mass are carried out here. A series of mechanics models for the sect from K254+895 to K254 +939 are established and mechanics analyses are carried out by means of load structure approach (LSA). Besides, the ANSYS software is applied to build the model of finite element method (FEM). Further, the results both from the LSA and FEM are also compared with to verify the veracity for each other.By analysis and appraisal of deformation and stability under different loads, the factors impacting on deformation of the tunnel are determined. From the results of analysis,reasonable prevention and cure measurements are suggested and corresponding rationalproposals for design, construction and operation are made also.