Research On Technology Of Shallow Excavation Tunnel Construction In Soft Soil Through Existing Railway

Since entering into the new century,with the development of city construction is the higher of the underground tunnel city needs more and people,border traffic is more and more rational,but the limited space and the current traffic situation already can not meet the development needs of human society,which requires us to develop underground engineering.However,both the existing geological,underground construction,ground transportation and other factors restricting the construction schedule,plan,cost.In this paper,Takeing Shijiazhuang six line tunnel construction across existing tunnel as the background,based on the literature review summarizes existing tunnel excavation,research background and research status and the tunnel in soft rock.The Shijiazhuang six line of the tunnel beneath the existing tunnel of Shijiazhuang Taiyuan line through the geographical environment,engineering properties,geological structure,hydrogeological,engineering characteristics and technical difficulties of analysis.By using the large-scale simulation software ANSYS to the Shijiazhuang six line in tunnel construction beneath the existing construction process through Shitai line tunnel are simulated.The variation of stress and deformation of surrounding rock of soft rock.(1)With the tunnel excavation,the surrounding rock in the compressive stress and tensile stress are changed,which is mainly due to tunnel excavation is equivalent to the unloading of surrounding rock of tunnel surrounding,broke the balance of hand makes the stress redistribution of the final change stress in surrounding rock.(2)Prior to the middle section of tunnel excavation,tunnel vault settlement,arch bottom uplift,arch foot horizontal wall and edge deformation is very small;when the tunnel excavation in the middle section,the horizontal displacement of the tunnel vault settlement,arch bottom uplift,the arch and side wall displacement increases suddenly,with the tunnel the horizontal displacement of the tunnel excavation,tunnel vault settlement,arch bottom uplift,the arch and side wall displacement tends to be stable.(3)Due to the large scale of the project,the construction content,the surrounding environment is complex,the construction period is tight,so the choice of reasonable organization and management mode,strengthen the site management coordination,is the successful completion of this project is an important part of.This requires the contractor to have a strong ability to allocate resources and on-site production capacity.(4)According to the characteristics of the tunnel excavation,use "in +CRD" construction,namely the CRD method excavation hole and hole on both sides by CRD method of excavation,this technology effectively solves the problem and provide a very valuable reference case for the industry.It provides a reference for similar projects.