Research On Deformation Laws Of Large Cross Section Shallow Soft Surrounding Rock Tunnel

With the rapid development of China’s economy, the road transport is also rapid development, including the highway tunnel. The highway tunnel is a kind of underground works, of which design and construction are subject to more uncertainties, compared to the ground works. Due to engineering geology, topography, environment and project cost, making the highway tunnel some special features, such as the characteristics of the soft surrounding rock, shallow, large cross section, small spacing, which make the design and construction more difficult, and the quality is also more difficult to control. Now lots tunnels with kinds of characteristics have been designed and built successfully. And many scholars analyze the measurement data at the site and use finite element analysis software to simulate tunnel excavation, just for analyzing and studying the law of the tunnel surrounding rock deformation timely and effectively, which provides a very useful value for similar tunnel construction. Kirin Cairn Tunnel, the engineering background of this article, has rare integrated features. Kirin Mountain Tunnel is a large cross section shallow soft surrounding rock tunnel. The difference is that analyzing and studying the law of surrounding rock deformation of the large cross section shallow soft surrounding rock tunnel is the main content.This paper is to analyze the the measurement data my research group got for a long time at the Kirin Mountain Tunnel construction site and use MIDAS/GTS finite element analysis software to simulate two-dimensional and three-dimensional excavation to Kirin Cairn Tunnel, then get the law of surrounding rock deformation of the large cross section shallow soft surrounding rock tunnel. The main work and conclusions of this paper are as follows:(1) According to the site measurement data, surface settlement shows a law of parabolic shape with the horizontal distance, and pesents a regular pattern like step-type with the construction phase.(2) With MIDAS/GTS finite element software simulating the Kirin Mountain Tunnel excavation of full cross-section, the CD method, double sidewall hole method, there are different surface and surrounding rock deformation laws after analysis and comparison.(3) Simulating Kirin Cairn Tunnel two-dimensional excavation of double sidewall hole multi-step method, and then it find that the surface and the surrounding rock subsidence curves are parabolic shapes、the surface horizontal displacement curve is a sine function shape etc.(4) Simulating Kirin Cairn Tunnel three-dimensional excavation of double sidewall hole multi-step method, and then it find the laws of settlement and horizontal displacement of the surfac、surrounding rock and the middle rock pillar, consistent with the construction phases.