Different Stress Field Weak Surrounding Rock Arch Tunnel Mechanics Trait Pilot Study

On the study of tunnel excavation, physical simulation can effectively simulate the nonlinear characteristics during failure of surrounding rocks. According to the choice of model material in general principle, the dissertation obtains model material that simulate reliably soft-weak surrounding rock in order to build physical model.In accordance with the key study on the twin-bore tunnel of soft-weak surrounding rocks in different initial stress, six physical runnel models with three lateral-compression coefficient (viz 0.5,1.0&1.5) are set up to study the mechanical characteristics of tunnels in the dissertation.Six models of twin-bore tunnel are set up to study the effect of the earth pressure distribution of surrounding rocks due to the different lateral-compression coefficient and construction. The relationships among the loosen zone of tunnel earth pressure, the tunnel excavated diameter, the different lateral-compression coefficient and the exposed time are revealed. Also, the dissertation discusses the interaction among surrounding rocks during the twin-bore tunnel construction. The failure mechanism with different lateral-compression coefficient during the long term safety is investigated.The process of constructing twin-bore tunnels is simulated by setting up the FEM model. The characteristics of the stress and displacement of tunnel surrounding rocks and tunnel linings in different initial stress are analysed.