基坑开挖对邻近盾构地铁隧道变形机制研究

Study on the Deformation Mechanism of Adjacent Shield Tunnel under the Excavation and Dewatering of the Foundation Pit

基于Mindlin理论对基坑降水开挖诱发邻近地铁隧道的应力应变及沉降进行理论研究。在结合逆作基坑实际开挖工况条件下,采用MIDAS/GTS大型三维有限元软件分析了基坑考虑不同降水情况下邻近盾构地铁隧道变形情况,并对不同模拟方案结果进行对比。结果表明,地铁隧道结构模拟结果合理,考虑降水情况下坑外土体的附加变形要比基坑开挖卸荷作用引起的土体变形大得多,抵消了隧道上抬变形趋势,使隧道产生了偏向基坑方向的变形,变形量值也大得多。

Based on the Mindlin theory, the stress strain and subsidence of adjacent subway tunnels areinvestigated theoretically. Using MADIS/GTS large 3d finite element software, the excavation of＇ lhe tbundat[onpit is investigated for the deformation mechanism of tile nearby shield tunnel. Based on the actual excavali（m con-ditions of the foundation pit, the deformation of the tunnel tunnel under different precipitation conditions is ana-lyzed and the results of different simulation schemes are compared. Results show that the subway tunnel structuresimulation resuhs are reasonable, considering precipitation down to the pit outside than of additional deformationof soil, soil deformation due to excavation unloading effect, offset the service tunnel deformation trend, make thetunnel produces to the direction of the foundation pit deformation, deformation magnitude is nmeh greater.