Study On External Water Pressure And Force Characteristics Of Tunnel Lining With Partial Blocked Drainage System

There are many mountainous landscapes in the southwest of China.Under the national strategy of western development,the demand for traffic development is extremely urgent.During the operation of the tunnel drainage system often causes a variety of reasons blocked,resulting in decreased drainage capacity.At present,in the calculation of groundwater around the tunnel,it is assumed that the status of the tunnel drainage system is completely symmetrical on the left and right sides of the section,but actual study shows the opposite result.Now the drainage system of the same state has been related to the study,but asymmetric blocked drainage system has not been researched.Research the seepage field of the deep tunnel with asymmetric blocked drainage system around tunnels by field experiment,theoretical analysis and numerical simulation,and find out the stress characteristics of the tunnel lining structure.Analysis the influence of Length of asymmetric blocked drainage system and design parameters of grouting reinforcement on external water pressure,stress and tunnel stability.The main contents and results are as follows:(1)Based on the collection of previous research results and data,the simulation of the drainage system in the tunnel construction of the blockage test.After drainage system asymmetric blocked,the pore pressure behind the secondary lining of the failure side will rise in a short time and then gradually decrease to stabilize.The longer the asymmetric blocked drainage system is,the higher the external water pressure is.Lining stress has not changed much at the normal side,and it has increased at the inner surface of the lining at the blocked side of the tunnel.Arch shoulder and arch waist at the most significant increase.(2)Analysised the method of numerical solution of Laplace partial differential equations with seepage.Using the PDE Toolbox to calculate the boundary conditions,analysis the numerical solution of the seepage field at different inside radius of tunnels and distal water pressure.The water pressure distribution curve behind the blocked side drainage system was obtained.(3)By introducing the complex plane conformal transformation,function image moving,Sturm-Liouville problem and separating variable method in mathematics,the formulas of the seepage field distribution and the percolation volume of the surrounding drainage system are obtained.The result was verified by numerical calculation method.(4)After the tunnel drainage system partial blocked,The secondary lining of the external water pressure is higher than the normal state.The longer the clogging length,the greater the pressure on the secondary lining.The water pressure on the secondary lining in the symmetrical blocked system of the drainage system is significantly higher than that of the asymmetrical blocked mode.(5)When the partial blocked length of the drainage system is different or the design parameters of the grouting reinforcement ring are different,the control factor of the lining safety factor is not surely the symmetrical blockage mode of the drainage system which can cause higher external water pressure.Therefore,when the tunnel design,if need to consider the impact of security when the drainage system blocked,the two types of drainage system blockage need to be both checked.(6)Increasing the thickness of the grouting reinforcement ring to improve the safety of the tunnel,when the grouting thickness is greater than a certain value,the two drainage system blockage patterns are possibly become the control factor of the safety of tunnel lining.The two drainage systems blockage patterns should both be checked for safety.