Study On The Interaction Of Adjacent Existing Tunnel And Deep Foundation Excavation

The excavation of deep foundation pit because of its complexity,comprehensive has always been a very important research topic.In recent years,with the rapid development of urban underground engineering,deep foundation pit engineering geological conditions and the surrounding environment is more and more complex,foundation pit construction area and adjacent existing tunnel distance is getting more and more near,how to not only ensure excavation of deep foundation pit construction progress but also to protect both the structural safety of the tunnel becomes the important problem to be solved.Therefore,for deep foundation pit excavation and adjacent existing tunnel interaction research has important theoretical significance and practical value.According to a deep foundation pit engineering in domestic,using finite element and finite difference method,considering the actual formation of tilted layer distribution,different branch door combination method.Numerical simulation of the existing tunnel,foundation pit excavation peripheral slope,slope in the excavation of deep foundation pit in the process of the rule of stress and strain of deep foundation pit excavation and adjacent existing tunnel interaction rules,the research results of the safe construction of the project and similar projects with theoretical support and reference value.The main research contents and conclusions are as follows:(1)deep foundation pit excavation on adjacent existing tunnel numerical simulation results show that,after excavation,the maximum deformation of tunnel lining occurred at the right hole near the foundation pit on the west side of the middle of the slope of the location,and to the ends of the tunnel gradually weakened;due to the effect of inclined strata,deep excavation rock of tunnel lining produced a reverse effect,and in close proximity to the foundation pit location of the tunnel lining produced deformation of uplift,but all deformation are in the scope of design,so the engineering of deep foundation pit excavation of tunnel effect is safe.(2)deep foundation pit excavation numerical simulation study shows that,deep foundation pit excavation is completed,the deformation of the foundation pit itself mainly concentrated in the pit bottom and sides,at the bottom of the excavation destroys the original should force balance in a certain place to uplift deformation,the soil around the foundation pit due to the influence by the tilted strata,deformation occurred in the middle part of the side walls of the circumference of the and deformation distribution and tilted strata distribution characteristics of highly consistent and maximum deformation occurred in the sandy mudstone layers.(3)numerical simulation analysis of the maximum principal stress distribution of the inclined rock strata,the stress distribution of the foundation pit and the stability of the slope of the existing tunnel.Studies show that deep foundation pit excavation is completed,the tunnel at the top of the slope deformation amount is small,not because of the excavation of foundation pit and lose stability failure;deep foundation pit excavation is completed,bolt stress overall smaller,only in the inclined strata boundary position due to the relative displacement of rock bolt with higher rates,other homogeneous formation due to homogeneous deformation bolt using rate is low.