Study On The Damage Mechanism And Defensive Measures Of Nanjing Metro Shield Underpassing The Ancient Ming City Wall

With a total length of 33.676 kilometers,the ancient Ming city wall in Nanjing is the longest city wall in the world and is known as the world’s largest city.Protection has received wide public attention.Improper construction will cause damage to the city walls and cause huge losses.The typical geomorphic and engineering geological features of Nanjing is summarized,and the numerical simulation methods are used to study the crossing points of Nanjing Metro passing through the Ming City Wall with typical geological conditions.The stability of the excavation face in the shield tunnel crossing the Ming City Wall is studied.The effects of tunnel depth,tunnel spacing,angles of penetration,cement grouting reinforcement depth and reinforcement depth on the deformation of the ground and city walls were analyzed.Provide reference for related projects.The research content and results of this article include:(1)The ground and building deformation caused by shield tunnels passing through buildings are systematically reviewed,and the research status of ancient buildings is summarized,especially shield tunnels through city walls,and proposes that shield tunnels cross city walls.Problems in the project are put forward.A site survey of the Nanjing City Wall was conducted.Based on relevant literature,the history,form,structure,common diseases,and protective measures of Nanjing City Wall are summarized.(2)The characteristics of Nanjing’s typical landforms and engineering geology are summarized.The Nanjing City Walll is partitioned based on Nanjing’s geomorphology and engineering geology conditions.The numerical simulation method is used to analyze the deformation of the ground and the city wall at the intersection of the Nanjing subway line and the city wall.(3)Taking the shield tunnel of Nanjing Metro Line 3 as a research background through the Wuyu interval wall project,the numerical simulation method is used to analyze the influence of the stability of the excavation surface,the depth of the tunnel,the distance between the tunnels,and the angle of crossing on the deformation of the ground and the city wall.