Research On The Influence Of Shield Construction On Ground Settlement And He Ping Gate

With the rapid development of our country’s economy and the acceleration ofurbanization, a large number of population is concentrating to the center city, as a result,the urban traffic demand increases sharply; On the other hand, it’s difficult to expandthe ground transportation, due to the constraint of the urban land resources,environmental protection, and urban traffic congestion problem become increasinglyprominent. In order to alleviate traffic pressure and solve the problem of urban trafficcongestion, the underground traffic system has become a hot spot in the development ofcities. Xi ’an is an ancient capital of civilization, national level historical and culturalcity in China and have many ancient buildings. The protection of ancient buildings is animportant problem if we want to construction subway tunnel in ancient buildingsdensely cities. This paper, taking xi ’an metro line4beneath the He Ping Gate as thebackground, research the influence of ground settlement and He Ping Gate by the shieldconstruction, through the theoretical analysis and numerical simulation. In this paper,the main work includes:Because of the different structure types and the change of geological condition, thedeformation allowed values of buildings is not the same. based on the investigation ofdeformation allowed values of similar buildings at home and abroad and the controlstandards of deformation when the subway crossing ancient buildings, the controlstandards of deformation of the deformation gradient≤1‰, the foundation settlement（+5~-20mm）is put forwarded, when the metro shield construction crossing the HePing Gate.The influence of two tunnel excavation at the same time and one after another under different channel distance in the process of shield construction is analyzed, andfind that the surface settlement of after excavation tunnel is slightly bigger than the firstexcavation tunnel when the depth of tunnel is defined; the maximum position of surfacesettlement is not at the top of the tunnel axis when the distance of two tunnel is veryclose;the surface settlement of excavation at the same time is larger than excavationone by one and for the special conditions of He Ping Gate the influence of discrepancyof surface settlement between excavation at the same time and one after another is verysmall,which can be neglected.The influence of grouting pressure, diameter of the excavation, jacking pressure,compression modulus of soil and lining stiffness to the surface settlement and He PingGate is researched and analyzed by setting up three-dimensional finite element model ofsoil-tunnel-structure. District is differentiated according to the severity that is affectedof He Ping Gate by shield construction Reinforcement scheme of ground stabilizationof sleeve-valve-pipe grouting for the area that is affected seriously is proposed.