OPTIMUM DESIGN OF THE BIG PIPE-ROOF IN LARGE-SPAN SHALLOW LOESS TUNNEL

摘要

Since Wenxiang Tunnel, a tunnel of Zhengzhou-Xi'an Passenger Dedicated Line in China, is a large-span shallow tunnel in loess, which under-passes the Lianhuo Highway, the surface settlement demands to be controled strictly. Big Pipe-roof is a very important technology of all measures to control the settlement of soil, So the longitudinal deformations of the pipe-roofs are monitored, the mechanical behaviors of the pipe-roofs are researched and the effect of control soil deformation is analysed at the test section. The results show that the force of pipe and surface settlement are a little large. Using finitedifference software FLAC3D to simulate the construction of undercrossing section, according to monitoring data to revise the calculation parameters of rock, comparing the surface settlement, plastic zone and deformation of pipe at the condition of the single layer pipe-roof with double layer pipe-roof. The calculation results show that the optimum design of pipe-roof can control over the deformation of soil and themselves better; the smooth run-through and monitoring data of under pass section prove further that optimizing the parameters of pipe roof is reasonably.