Vibration Test And Analysis Of Water-Rich Loess Tunnel For High-Speed Railway

The construction of big cross section water-rich loess tunnel in railroad passeng er transportation special line was still for the first time in domestic and foreign. the re will be more and more resembling projects in the water-rich loess area with the infrastructure construction and development of western region of our country. The ol d loess Located at saturated loess tunnel's basis, under present subterranean bottom strengthening works measure, whether not to be argillitization or softening, satisfies the subsidence request, guarantees line's security, the stability and smoothness on hi gh-speed trains moving loads. vibration-exciting test is the most direct, efficient and reliable Proof technique.In this paper, vibration-exciting test is carried on the tunnel located in Mianch i to Lingbao section of Zhengxi railroad passenger transportation special line named Zhangmao.Simulated dynamic loads of train on tunnel rail base plate, vertical vibra tion speed and soil pressure from Tunnel rail base plate top surface to 3 meters bel ow the Invert are masured, soil pressure and water pressure alone the invent, the st ress inside the concrete filled in Invert are also be masured, distribution and variati on of vibration velocity, soil pressure, water pressure, dynamic stress in Different vi bration frequency are fined. Through the analysis and comparison of the vibration v elocity, the dynamic sounding and the grading curve before and after the vibration-exciting test,considering the accumulation subsidence=0.5mm, the stability and long-term security the tunnel in dynamic loading be verified.When dynamic pressure is about 30kPa upon the base plate top, the maximu m dynamic strain of concrete filled is 1με, far less than concrete cracked strain; Co nverted to the biggest dynamic stress is 30kPa,0.2%of the C30 concrete compressi ve strength design value; The thickness of packing concrete definitely may optimize.Through finite element method, take shaking speed as the index studying, anal yse the stability of water-rich loess consolidating two kinds condition with bottom 1 oess in having the jetting concrete or not. got the conclusion that the 20cm jetting concrete under Invert shoud be optimize.