Grouting Reinforement Study Of Mountain Tunnel Based On Fluid-solid Coupling Theory

The problem of tunnel seepage exists from the construction to open to traffic and operation.However,the technology of deep mountain tunnels construction in water-rich regions is not very mature.Currently the main method to solve the problem of seepage is preliminary grouting reinforcement on tunnel,which can form a water curtain.This method is maximum protection of groundwater resources,Improve the waterproof ability of tunnel surrounding rock,reducing the tunnel water gushing disasters occur.Based on fluid-solid coupling theory of Tunnel,This paper investigates the regularity of pore pressure,stress,displacement and plastic zone development in surrounding rock and lining of the tunnel when grouting reinforcement rim thickness and permeability coefficient changes,using the means of combination of theoretical analysis and numerical simulation.It not only riches and expands theoretical knowledge,but also has certain reference value to the following actual engineering.The main researches have been conducted as follows:(1)Through the analysis of the tunnel seepage theory and deduction of water pressure formula,water inflow formula of surrounding rock and lining structure,combined with example calculation of Caojiagou tunnel,it shows that :it is obviously that pore pressure and seepage flow of the lining structure decrease with grouting reinforcement rim.Along with the increase of thickness of grouting reinforcement rim and the decrease of the permeability coefficient,the pore pressure and seepage flow of the lining initially decrease rapidly.But it decreases slower gradually,finally keeps unchanged.(2)The results of numerical simulation show: The increase of grouting reinforcement rim thickness and decrease of permeability coefficient has good effect on the control water pore pressure of lining.But when the thickness of grouting reinforcement rim is more than 6 m,the change of pore water pressure amplitude of the lining is small.With the decrease of the permeability coefficient,water pressure trend of the lining is slow.The emergence of the grouting reinforcement rim will greatly change the tunnel seepage law.Seepage vector diagram shows: the increase of thickness and the decrease of permeability coefficient of grouting reinforcement area will generate excess pore pressure and increase the plastic area near hance in the reinforcement area.(3)The change of the thickness of the grouting reinforcement has a significant effect on the settlement of the vault,but it has limited effect on the arch-uplift and the arch-waist contraction.While the change of permeability coefficient has little influence on the vault settlement and the uplift of the arch.With the decrease of the permeability coefficient,the horizontal displacement at the arch waist will increase correspondingly,but the increasing amplitude will gradually decrease.(4)The maximum compressive stress of the tunnel will appear in the vicinity of the arch foot,and the arch and vault are locally tensioned in different working conditions.With the increase of the thickness of the grouting consolidation zone or the reduction of the permeability coefficient,the secondary lining cloud pattern shows the transformation from compressive stress to tensile stress.When the thickness reaches 6m,the range and the numerical values of tensile or compressive stress are basically stable,no longer developing with the grouting parameters and the effect of the grouting circle on the strengthening the surrounding rock is no significant.