The Influence Of Water Blocking And Drainage On The Stability Of Surrounding Rock Seabed Tunnel With Typical Characteristics

With the steady and rapid development of Chinese economy,the timeliness of the demand human resources transportation among regions is increasing.Due to its advantages such as not being affected by bad weather,not occupying navigation channel,occupying less land and having good structural durability,the submarine tunnel has gradually become the primary choice of cross-sea traffic route for human beings.Hence,the influence of the degree of sealing of the lining structure and the permeability of the surrounding rock on the stability of subsea tunnels has always been the main topic of relevant engineering researchers.This paper takes the Qingdao Metro Line l submarine tunnel project as the research background and analyzes the existing research in depth.On the basis of the results,the theoretical analysis and numerical simulation methods are used to systematically analyze and study the influence mechanism of the permeability coefficient of the lining structure and the permeability of the surrounding rock on the stability of the subsea tunnel.In this paper,based on the analytical solution of the seepage field of the subsea tunnel,the relationship between the lining stress and the self-permeability coefficient is analyzed,and theoretical support is established on the subsequent research.Then using Qingdao Metro Line 1 as the engineering background,FLAC3D numerical simulation software is utilized to analyze the effects of different permeability coefficients of lining structure and the surrounding rock on the stability of submarine tunnel under the action of fluid-solid coupling.Thereinto the lining aspect judges the stability of the lining structure through the stress and displacement of the lining structure.At the same time,the method of judging the stability of the lining structure by stress is to calculate the axial force and bending moment of the vault,the arch waist,the arch foot and the invert arch to judge the safety factor;the method of judging the stability of the lining structure by displacement is to calculate the two parameters of the dome settlement and the arch convergence to compare the different working conditions.In the surrounding rock,the stability of the rock mass is analyzed by the displacement of the rock mass around the cavern and the distribution of the plastic zone.It is found that when the permeability coefficient of the lining is higher,the safety coefficient of each part of the lining structure is lower,the settlement of arch roof and the convergence of arch foot are higher,which is the more unfavorable to the stability of the subsea tunnel.When the permeability coefficient of the surrounding rock is larger,the stability of the surrounding rock is worse,which shows that the pore water pressure increases,the displacement of the rock mass around the cavern increases,and the plastic zone expands.Meanwhile,the influence of the lining permeability coefficient on the stability of subsea tunnels increases with the permeability of surrounding rock.Finally,the influence of permeability coefficient of lining structure on the stability of submarine tunnel is analyzed under different degrees of influence of fault fracture zone.Through the research,it is found that when the submarine tunnel crosses the fault fracture zone,it will have a greater impact on the stability of the subsea tunnel itself.When the degree of the influence of the fracture zone is greater,the safety factor of each part of the lining structure is lower,the convergence of the arch settlement and the arch is greater,and the influence of the permeability coefficient of the lining structure on the overall stability of the subsea tunnel is greater.In this paper,the influence of the change of permeability coefficient on the stability of submarine tunnel lining structure under different characteristics of surrounding rocks is studied,which could bring guiding significance to the construction of submarine tunnel under different characteristics of surrounding rock and the selection of sealing degree of lining structure.