The Research On Mechanical Characteristics And Reasonable Grouting Parameters Considering The Coupling Of Fluid And Solid In Water-rich Tunnel With Soft Rock

With the rapid development of China’s transportation industry, a large number of highways and railways construct in the water-rich strata with soft rock. In the tunnel construction, dome collapse and deformation often increase the project investment and construction difficult. At present, the research of water-rich tunnels with soft rock mainly focuses on the adverse effects and appropriate controlling measure of the soft rock’s low mechanics parameters, ignoring the mechanical effect of groundwater seepage. The researches from the perspective of fluid-structure interaction have yielded some results, but not deep enough. With Nan Shan-zhai tunnel which is a part of Hunan Province Ji-Huai highway as background, the main research contents are as follows:(1) On the basis of expound the fluid-structure interaction theory and its basic equations, this section expounds the effect between groundwater and rock, including the mechanical effect of groundwater on rock, and weakening effect of groundwater on rock strength, seepage reducing the stability of the excavation face.(2) Through the establishment of contrast conditions, study the deformation and stress characteristics of the fluid-structure interaction effect, and obtain the influence trend and extent of the seepage field.(3)By numerical simulation method, study the influence to seepage field, stress and displacement distribution of surrounding rock and support structure by the seepage control factor, such as groundwater level and limited drain, to provide the theoretical basis for the stress and deformation control in the actual construction process.(4) To understand the mechanical effect of grouting in a more intuitive way from the perspective of coupling of fluid and solid, only consider the reduction of the permeability coefficient by grouting, study the reasonable grouting parameters from three factors:the thickness, permeability coefficient and scope.(5) With Nan Shan-zhai water-rich with soft rock tunnel which is a part of Ji-Huai highway in Hunan province as background, make numerical analysis of a typical section. And monitoring the support deformation, the rock pressure and the second lining stress, compared with the numerical results and verify the reliability of the numerical calculation.