Study On Water Pressure And Grouting Circle Parameters Of Lining In Zhaojiayan Tunnel

With the implementation of the “Belt and Road” policy,the scale and number of national infrastructure constructions have grown rapidly,and the number of tunnel projects has also increased rapidly,playing an irreplaceable role in the development of the national economy.The investigation found that during the actual operation of the tunnel,the tunnel lining structure is often damaged to varying degrees.There are many reasons for the damage,such as changes in geological conditions,changes in external loads,temperature changes,etc.Lining water pressure is also a reason not to be ignored.It is very important to deal with the relationship between the tunnel and groundwater,and study the influence of groundwater on the tunnel lining water pressure,which is of great significance to ensure the safe operation of the tunnel.Groundwater exists in the underground rock mass.When the tunnel is constructed,depending on the amount of water and its impact on the project,the groundwater can be treated in different ways.It can be classified into three types: full discharge,full plugging and plugging-limited discharge.Models,using different treatment models,will affect the distribution of underground seepage fields and thus the lining water pressure.Therefore,three types of model studies can be conducted.The Zhaojiayan Tunnel is a rich water mountain tunnel.The groundwater is abundant and the surrounding rocks are broken.In actual construction,the tunnel is mainly used in the "full drainage" mode.Long-term drainage is easy to block the drainage system,and it is necessary to pressure the tunnel lining.For further research on the role,this article takes the Zhaojiayan Tunnel as the basis,obtains basic data through actual engineering surveys,and uses a combination of analysis and numerical simulation methods.Completely impervious and using grouting to block water,"mainly plugging-limited discharge",that is,the tunnel lining is not fully permeable and grouting the surrounding rocks.Three types of water drainage modes are introduced to reveal the distribution of seepage fields under different water drainage modes The law and the effect of water pressure on the lining;The reasonable parameters of the grouting circle of the tunnel lining are studied.Through the research of this paper,the following conclusions are obtained:(1)In the natural seepage field,the pore water pressure value is not distributed horizontally,but along the slope of the ground surface,a certain hydraulic slope is formed.The water pressure value in the formation is approximately equal to the hydrostatic pressure value.(2)In the "full row" mode,the seepage field in the surrounding rock of the tunnel presents an approximately concave precipitation funnel.The pore water pressure in the outer ring of the lining is almost completely dissipated.The upper part of the groundwater on the shallower side of the tunnel has the most groundwater.It is easy to dissipate,and the maximum lining water pressure occurs at the arch foot part on the deeper side.(3)In the "full block" mode,no matter whether the permeability coefficient or thickness of the grouting ring is changed,it has no effect on the lining water pressure.(4)Under the drainage mode of “mainly plugging and limited discharge”,the reduction of the grouting ring and the lining permeability coefficient has a significant effect on the lining water pressure,and the thickness of the grouting ring has a small effect on the lining water pressure.When the permeability coefficient is reduced from 2.68 × 10-5 to 2.68 × 10-6,or when the lining permeability coefficient is increased from 3.06e-6 to 3.06e-5,the water pressure coefficient of each part of the lining changes most significantly,and the grouting continues to be reduced.The value of the ring permeability coefficient or increasing the lining permeability coefficient value will only increase the cost and have no obvious effect on the lining water pressure.(5)The relationship between the tunnel seepage volume and the grouting ring parameters is as follows: the tunnel seepage volume decreases as the grouting ring thickness increases;when the tunnel grouting ring thickness is constant,the tunnel seepage volume decreases with the grouting ring permeability coefficient Decrease;when ng?459 and grouting ring thickness ?4m,the effect of increasing grouting ring thickness and decreasing grouting ring permeability coefficient on tunnel seepage is not obvious.(6)Through comprehensive comparison and analysis of theoretical calculations and numerical simulations,it is concluded that the tunnel adopts the mode of “mainly plugging and limited discharge”.The permeability coefficient of the grouting ring is 2.68 × 10-6,the thickness of the grouting ring is 2m,and the lining penetration When the coefficient is 3.06 × 10-5cm / s,the construction is the most economical and safe,and the lining water pressure control effect is the best.