Research On Construction Influence Of High Speed Railway Tunnel Through Highway In Loess Area

China is the most widely distributed loess country all over the world, the loess area of which is up to 631,000 square kilometers, accounting for 6.3 percent of China’s land area.With the rapid development of China’s transportation industry, more and more high-speed railway tunnel need to pass through the loess areas, even closer to the existing building (structure). Located in the new railway Mianchi to Lingbao section of passenger dedicated line from Zhengzhou to Xian,Wenxiang tunnel,under Lian-Huo highway, with maximum excavating area up to 174.8m2, is a rare large-section tunnel in loess region. In view of their engineering properties of loess, how to ensure the normal traffic of Lian-Huo highway during construction of tunnel is a serious problem.In a setting of the construction for Wenxiang tunnel on passenger dedicated line from Zhengzhou to Xian passing through Lian-Huo highway nearly, in this paper, the influence of tunnel excavation under different conditions on surface subsidence was analyzed by using finite-difference software FLAC3D;in the meanwhile, with reference to data based on in-situ monitoring, engineering measures of controlling ground surface settlement was investigated and the major research results were as follows:1.On the basis analysis of related literature and similar project cases at home and abroad, combined with field monitoring data based on engineering test and the results of simulation, the control standards in loess region concerning about surface subsidence is given in the construction of highway tunnel passing through the surface nearly.2.Simulation tests is adopted in this project to study the rule of the surface subsidence and ground subsidence caused by dynamic tunnel excavation. The surface subsidence caused by tunnel construction in loess region can be divided into four stages based on the simulation test3.Using finite-difference software FLAC3D, the research is mainly focused on the influence about the buried depth and the excavation method on the settlement of highway in order to get the relationship of tunnel buried depth about maximum ground subsidence and subsidence of width. In the meanwhile, double side drift method is more advanced than the CRD method to control the surface subsidence for the tunnel at a certain depth.4. According to the analysis of the surrounding rock pressure test data, the soil pressure distribution is X approximately and the soil pressure in the hance and sidewall is bigger after the tunnel surrounding rocks stay stable.5.Making a combination of theoretical analysis and field construction methods, measures can be taken to control surface subsidence in Wen tunnel passing through Lian-Huo highway nearly including optimizing the construction technology, closed in time, strengthening the advance supporting and initial supporting, etc.