Research On Mechanical Effect Of Mud-sandstone Interbed Tunnel Under Seepage

With the gradual advancement of China’s transportation power strategy,it is difficult to avoid the situation of encountering long,large and deep tunnels in the process of transportation construction.In the process of tunnel construction,there are more and more cases that need to pass through water-rich strata,among which water-rich rock masses with mud-sandstone interbeddings are very common.In the construction of the tunnel,engineering disasters such as large deformation of the vault,severe cracking of the supporting structure,and landslides often occur in water-rich stratum.Therefore,it is significant to study the mechanical effects of mud-sandstone interlayer tunnels under seepage.At present,there are few studies on the stability of mud-sandstone interlayer tunnels under the action of seepage.Based on the liangjiang tunnel of Chongqing Yuchang expressway,this paper mainly studies the mechanical effects of the mud-sandstone tunnel under the action of seepage from the following aspects:(1)Based on a lot of research data at home and abroad,the basic theory of fluid-solid coupling is comprehensively expounded.Based on the actual project,a comparative case is considered to consider fluid-solid interaction and unconsidered fluid-solid interaction,through comparing and analyzing between the seepage effect of mud-sandstone interbed of tunnel surrounding rock and supporting structure.The effects of fluid-solid coupling on the seepage field,displacement field,stress field,plastic zone,bolt stress and lining stress are analyzed.(2)The accuracy of the numerical simulation results is verified by comparing the actual monitoring measurement data of arch subsidence and peripheral convergence with the numerical simulation results.It provides a theoretical basis for the stress and strain control in the actual excavation process;(3)Through MIDAS/GTS finite element software,the distribution rules of the surrounding rock seepage field,displacement field,stress field,plastic zone,bolt stress and lining stress were studied when the interbedded mud-sandstone tunnel was controlled by different apparent inclinations,dip angles and interbedded thickness.