盾构隧道双线斜跨既有隧道施工变形影响研究

Study on Influence of Construction Sequence of Left and Right lines of Shield Tunnel on Deformation of Existing Tunnel

针对某地新建地铁隧道斜穿上跨既有地铁隧道形成的双层四线叠交隧道的近接施工问题,采用基于有限差分法的数值模拟手段,深入研究了新建隧道左右线不同施工方案对既有线的变形影响规律。结果表明:(1)先左后右施工方案中,新建隧道左线通过四线叠交处至新建右线掘进到达四线叠交处,既有线左线拱顶、拱底位置处竖向位移变化幅度较大,分别为655.22%、920.04%;(2)先左后右施工方案中,新建隧道右线通过四线叠交处至施工结束,既有线右线拱顶、拱底位置处竖向位移变化幅度较大,分别为174.46%、191.45%;(3)先右后左施工方案中,新建隧道右线通过四线叠交处至新建隧道左线掘进到达四线叠交处,既有线右线拱顶、拱底位置处竖向位移变化幅度较大分别,为524.09%、744.87%;(4)先右后左施工方案中,新建隧道左线通过四线叠交处至施工结束,既有线左线拱顶、拱底位置处竖向位移变化幅度较大,分别为217.94%、223.92%;(5)既有隧道左线、右线左、右拱腰最大水平位移绝对值先右后左施工方案分别为先左后右施工方案的3.99倍、3.53倍、2.03倍和8.12倍。从横断面方向看,距既有线远侧隧道线先施工,近既有线隧道线后施工,既有线所受整体影响更小。

For the adjacent construction of a double-deck four-line overlapping tunnel formed by a newly-built metro tunnel crossing obliquely over an existing metro tunnel in a certain area, numerical simulation based on the finite difference method was adopted to study the influence of different construction schemes for the left and right lines of the newly-built tunnel on the deformation of the existing tunnel line. The results showed that: 1) In the "the left line prior to the right line" construction scheme, the left line of the newly-built tunnel passes through the four-line intersection to the newly-built right line and reaches the four-line intersection. The vertical displacement at the top and the bottom of the left-line arch of the existing tunnel varies sharply, i.e. 655.22% and 920.04% respectively;2) In the "the left line prior to the right line" construction scheme, the right line of the newlybuilt tunnel passes through the four-line intersection to the end of construction, and the vertical displacement at the arch top and bottom of the right line of the existing tunnel varies greatly by 174.46% and 191.45% respectively;3) In the "the right line prior to the left line" construction scheme, the right line of the newly-built tunnel passes through the four-line intersection to the newly-built left line and reaches reach the four-line intersection. The vertical displacement at the top and bottom of the right line of the existing tunnel is 524.09% and 744.87% respectively. 4) In the "the right line prior to the left line" construction scheme, the left line of the newly-built tunnel passes through the four-line intersection to the end of construction, and the vertical displacement at the arch top and bottom of the right line of the existing tunnel varies greatly by 217.94% and 223.92% respectively;5) In the "the right line prior to the left line" construction scheme, the absolute maximum horizontal displacement of the left line, the left line and the right arch waist of the existing tunnel is 3.99 times, 3.53 times, 2.03 times and 8.12 times those of "the left line prior to the right line" construction scheme. Seen from the cross-sectional direction, the construction of the tunnel line far from the existing tunnel line prior to that of the line adjacent to the existing tunnel line can exert less impact on the overall project.