Analysis Of The Influence Of Underground Structure Construction On Underlying Tunnel

China’s economy and urban construction have developed at a high speed accompanied by the rapid urban development.As the urban scale expands and urban population booms,the limited land in cities can no longer meet the requirements of urban construction and development,as a result,many cities in China have traffic congestion,housing shortage and other problems.Under the circumstances,metro,a new type of urban traffic with the merits of large volume,high speed,punctuality,environmental protection and safety in use,emerges at the right moment,and has gradually become the focus of urban traffic construction.However,many new issues have been exposed as metro develops excessively,for instance,problem of crossing existing structures,problem of the influence of underground construction on existing tunnels and so on.To reduce the harm to tunnel caused by construction,further analyses and researches on the influence of underground structure construction on tunnels need to be conducted,and effective engineering technical measures should be adopted to avoid or alleviate the damage to existing tunnels.Based on the South Square project of Hefei South Railway Station,the impact of underground structure construction on the underlying tunnels is addressed,and the achievements of the predecessors are reviewed and summarized in this paper.Moreover,analyses on the mechanism deformation of underlying tunnel triggered by underground structure construction is conducted.MIDAS GTS software is used to establish 3D models of foundation pits and tunnels,and the result of simulation data under different working conditions are analyzed and compared.Conclusions are as follows:(1)By reviewing literature and analyzing theory,researches on the deformation mechanism of existing tunnels that close to underground structure construction were made.(2)The numerical analysis model was built by applying the finite element software M I DAS GTS and numerical datum were respectively calculated under different working conditions.Thus obtaining the subsidence law of foundation pit backfilling on the underlying tunnels,that is the whole deformation trend presents arched shape with a large center and small sides.(3)By analyzing the causes of the deformation of underlying tunnels,foundation pit backfilling on the subsidence of underlying railway tunnels is positively correlated with covering soils,the more the covering soil,the larger the deformation;but it is negatively correlated with distance,the far the distance,the smaller the settlement.Figure 26;table 4;reference 47;...