| With the development of economy,the center of national infrastructural investment is transferring to central and western region in China gradually.In the process of developing west contain complex terrain,the soft and loose carbonaceous shale with low strength at high altitude and cold regions belongs to geological rock when constructing highway tunnels,There will be a series of engineering and large deformation troubles when passed through by the tunnel.Taking Jiangluling tunnel which located in the highway from Gonghe to Yushu,Qinghai province as an engineering example,aiming at the problem of large deformation of soft rock in constructing,the mechanism of large deformation and measures of construction have been studied by using theoretical analysis,on-site monitoring,numerical simulation and summary.The main contents and results are listed as follow:(1)The mechanism of large deformation is summarized based on engineering mechanical properties,failure characteristics and causes of large deformation.According to monitoring date,the regulation of deformation and depth in Jiangluling tunnel is concluded,and 100 meters depth is the deformed turning point of carbonaceous shale tunnel.(2)Some suggestions and measures about carbonaceous shale tunnel during excavation are putted forward for controlling large deformation based on construction and supporting in Jiangluling tunnel.(3)On the base of site-on monitoring date,displacement curve of carbonaceous shale tunnel is drew,and the regulation of deformation is analyzed in detail,furthermore the corresponding regression function is calculated.The stress of rock and supporting is analyzed by using the date of pressure cell and steel bar gauge.(4)The drilling footage,core soil length and distance of I-steel in three-bench seven-step excavation method are simulated in detail by using numerical simulation.And obtain that the results of I-steel from numerical simulation accord with monitoring date. |
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