盾构近接高架桥桩施工的地层沉降空间形态研究

Spatial Form of Stratum Settlement Induced by Excavation of Double Shield Tunnel Approaching Piles

为了解盾构近接施工引起地层的非线性变形和沉降空间形态,基于有限差分法对合肥地铁1#线隧道近接城市高架桥桩的盾构推进过程进行了研究,分析了盾构近接桩体施工前后横向、纵向地表非线性沉降变化规律及地层沉降空间分布形态。结果表明,近距双线隧道盾构依次开挖对土体产生扰动以及盾尾空隙引起地层不均匀沉降,由于近接高架桥桩基的影响,其沉降量与盾尾空隙后方距桥桩距离成函数对应关系,相邻隧道开挖引起的地层沉降对沿隧道轴线的地表沉降具有叠加效应。数值模拟实现了隧道地层沉降空间形态等值超曲面图和地表沉降曲面图对地层不均匀沉降等值3D形态的描述。

The spatial form of stratum settlement is difficult to characterize during approaching piles excavation in shield tunnel.In this paper,the finite difference method is used to analyze the process of shield advancing adjacent to urban viaduct piles in Hefei metro line 1.The change law of lateral and longitudinal ground nonlinear stratum settlement and spatial distribution pattern of stratum settlements are analyzed before and after the shield excavation approaching the viaduct pile.The research results show that,due to the influence of viaduct pile foundation,the soil disturbance and shield tail interspace are caused by double-line shield tunnel excavation in turn and stratum loss which leads to uneven stratum settlements,and has a function for the correspondence between the settlements and the distance of the interspace behind the shield tail and viaduct piles.Stratum settlements caused by tunnel excavation and surface settlements along the tunnel axis have additive effect.Numerical simulation achieves the description of the surfaces of the equivalent tunnel ground settlement space and the equivalent 3D shape of the ground settlement surface and the non-uniform settlement surface.The research results have a certain reference value for the research on spatial form of stratum settlement during shield construction adjacent to viaduct piles.