The Stability Analysis Of Tunnel Considering Fluid-Solid Coupling And Time Effect

China is the country had the largest number of tunnels, the fastest development of technology, the most complex geological conditions and different structures. Most of these tunnels are troubled with the seepage and time effect, which are vital importance of the stability of the tunnel. Not only the cost of construction will be greatly increased, but also a catastrophic accident if mishandled, cause a serious threat to the safety of constructors. The focus of this study is on fluid-solid coupling and rheological characteristic of weak surrounding rock, the main works and results are as follows:(1) Method for quantitatively evaluating stability of surrounding rock of tunnel is discovered, the calculating formula of Zone State Index (ZSI) is derived by means of stress and strain state of rock mass, and the stability of tunnel is judged by the value of ZSI. The correctness of the method is verified by comparing the typical problems in geotechnical engineering, which provides the basis for the study of the fluid-solid coupling and the time effect of the tunnel.(2) The formula that the permeability coefficient of the rock mass is changed while the strain state changing can be concluded through the relationship between the ZSI and the zone permeability, FISH language is used to make it work in the FLAC3D. This formula is applied to 202 Section of Dalian Metro, and the analysis of stability of shield tunnel face shows good agreement with the actual monitoring data.(3) In view of the time effect of surrounding rock, a model is proposed to describe the creep of rock and soil, which is the nonlinear Nishihara strain-softening model-NNS model. Newton element is processed as nonlinear element in this model and the Strain-softening plastic element is added in order to decrease the parameter value with the increase of time and strain, and lead the accelerate creep stage. In addition the identification method of each parameter of NNS model is provided.(4) Secondary development of NNS model is taken out, and technology roadmap is provided and successfully achieved it, moreover, NNS model is verified in view of elastoplasticity, viscoelasticity and visco elastoplastic.(5) NNS model is applied to research the rheological properties of surrounding rock of Dalian Chenjiadian tunnel, and the reasonable construction time of second lining is identified. This model provides reference for similar projects and has a certain practical meaning.