Study On The Tunnels Stability Influence Of Caverns In Arch And Waist In Surrounding Rock

With the increasing development of China’s large-scale highway construction,highway tunnel construction has made a very big step forward. However, due tothe special nature of the highway tunnel, climatic conditions, terrain conditions,geological conditions and the design, construction, operation and management, repair and reinforcement in a variety of adverse factors, the initial support lining behind a lot of highway tunnel surrounding rock appeared a wide range of hollow,resulting in a highway tunnel built, the tunnel structure varying degrees of complicated and changeable diseases brought great security risk to the normal transportof highway tunnel.TUNNEL behind the existence of a variety of sizes, a variety of shapes emptywhen the overall structure of the tunnel, this paper has built an instance of the tunnel project, loving mother mountain tunnel to establish a three-dimensional elastic-plastic finite element model for analysis by numerical simulation. In this thesis, was triangular, rectangular and trapezoidal shape of the voids on the overall structure of the tunnel in the tunnel arch, arch waist position. For each type of anempty, were established at different radial length, different heights, different ringwidth empty finite element model. Analysis of tunnel surrounding rock displacement, in different conditions of stress variation and a variety of hollow below the initial support tensile stress, compressive stress variation. When the initial support structure behind voids will cause re-segment of the surrounding rock stress, resulting in segments law more complex. Not just stress-strain analysis of the structure of the tunnel size. Have to study, analyze the variation of voids on the overall structure of the tunnel instability and failure. So special introduction of finiteelement strength reduction, specific convergence criteria calculated factor of safety of the tunnel structure, to comprehensive evaluation of voids on the overall structure of the tunnel.The results show that: the construction of the tunnel in level IV surrounding rock conditions, when the initial support structure behind the existence of differentshapes, different sizes of empty, empty displacement the the rock compressive stress in the vicinity and empty tunnel overall impact is relatively small; when empty volume increases, the bottom of the empty primary support stress there will be varying degrees of increase, the ring size changes empty the greatest impacton the initial support stress.The conclusion that the overall structure of the tunnel by the different sizes, different shapes empty investigated as follows: different directions void size on the impact of structural safety factor in descending order: radial, height, circumferential direction. And when the hollow ring to a width of5.0m, lower safety factor of tunnel structure more apparent.