Study On The Effect Of External Water Pressure On Lining Structure In ZhongLiangshan Tunnel Of Chenyu Expressway

Water pressure occurs repeatedly during the process of tunnel construction.In the complicated topography and geology,it can not be neglected that groundwater will influence the safety of tunnel engineering.With the rapid development of transportation industry,one will inevitably construct tunnels through mountains in the process of tunnel construction.Because of the diversity of terrain conditions in construction zone,one is bound to construct numerous tunnels through mountains when the construction route must pass through mountains.Thus,it is common to construct mountain tunnels in high water pressure and water-enriched region.However,in the process of tunnel construction,how to do with groundwater has been an important and difficult problem which needs to be solved at home and abroad.“All blocked” or “all emissions” is an early tunnel waterproof and drainage way.However,it is not favorable for the sustainable development and not incompatible with the principles of environmental protection;but “water plugging predominantly with limited emissions” is more scientific and rational.By controlling the amount of groundwater infiltrating into tunnels and tunnel water emission,tunnel safety can be guaranteed;the environment of tunnel construction zones will not be damaged;residents' life and production will not be affected.At the same time,investment costs and uncontrollable risks in construction period can be reduced.This thesis,by analyzing the example of ZhongLiangshan tunnel in Chengdu-Chongqing expressway,will focus on the effect of groundwater on the safety of lining structure.Moreover,it will combine theoretical analysis,numerical model calculation and some other ways to study water pressure on lining structure.The research contents and methods are as follows:(1)First,it will briefly state some ways to study external water pressure in tunnels and treat groundwater.Second,it will discuss the influence of groundwater on tunnel structure.Third,prediction methods on tunnel discharge will be determined by combining theories.(2)By deriving the theoretical formula of groundwater infiltration and adopting analytic method,one can know the interrelation between external water pressure in tunnels and lining structure.Then,by applying the formula,this thesis will analyze tunnel lining,the thickness and permeability of grouting circle and the relationship between grouting technology in different levels of surrounding rocks and the reduction coefficient of external water pressure in lining structure.It turns out that with the increase of lining structure and the coefficient of permeability in grouting circle,water pressure in lining will increase correspondingly.On the contrary,with the increase of the grouting circle thickness or the coefficient of permeability in lining structure,water pressure in lining will decrease.(3)By applying ABAQUS finite element software and numerical calculation model of water pressure to analyze elements,then comparing it with theoretical and numerical solutions,this thesis will analyze the force on lining and the influence of water inrush in tunnel vaults on lining structure in different grouting levels and different grouting circle thickness.