盾构下穿施工对软流塑地层及既有隧道变形影响分析

Analysis of the Influence of Shield Tunneling on the Deformation of the Soft Flow Plastic Stratum and Existing Tunnel

新建城市地铁下穿既有运行地铁现象增多,其施工对地表构筑物,既有地铁的运行安全是必须考虑的问题。以南京地铁5号线三山街站-朝天宫站区间盾构隧道下穿既有地铁1号线隧道为工程背景,进行了室内物理模型试验和有限元软件Midas-GTS NX对双线盾构隧道掘进过程进行了动态模拟,揭示了地层及既有隧道的变形受盾构隧道施工的影响。结果表明:盾构正交下穿既有隧道施工时,地层和既有隧道将产生较大的不均匀沉降,同时对既有隧道的产生较大的水平位移,造成隧道产生扭转变形,严重影响隧道运营安全,并建议对正交区域进行加固处理。

Newly built urban subways have increased the phenomenon of running existing subways,and the construction of existing subways on the ground surface,and the safety of existing subways must be considered.In this paper,an indoor physical model test and finite element software Midas-GTS NX were used for the double-line shield tunneling based on the engineering background of the shield tunnel of Sanshanjie Station to Chaotiangong Station of Nanjing Metro Line 5 crossing the existing Metro Line 1 tunnel.Dynamic simulation of the tunnel digging process revealed that the deformation of the stratum and the existing tunnel was affected by the construction of the shield tunnel.The results show that when the shield tunnel passes through the existing tunnel orthogonally,the ground and the existing tunnel will have a large uneven settlement,and at the same time,the existing tunnel will have a large horizontal displacement,which will cause torsional deformation of the tunnel and seriously affect the tunnel.Tunnel operation is safe and it is recommended to reinforce the orthogonal area.