建筑偏载下大直径盾构隧道开挖面稳定性数值模拟分析

Numerical Simulation Analysis of Excavation Face Stability of Large Diameter Shield Tunnel Under Building Eccentric Load

现有盾构隧道开挖面稳定性研究主要集中于分析地表无建筑荷载下的盾构开挖面稳定性问题,而在实际工程中,盾构开挖面附近往往有建筑物,有必要考虑邻近建筑荷载对盾构开挖面的影响。通过建立三维有限元模型,研究了黏土地层中地表建筑偏载作用下大直径盾构开挖面失稳演化特点。研究表明:当开挖面支护比在0.6~1.0时,地表建筑对开挖面位移影响不大;当支护比小于0.3时,地表存在不平衡建筑荷载,导致盾构开挖面前方土体位移增大,且失稳影响区域远大于无建筑的情况;随着支护比下降,开挖面前方土体逐步发生沉降,沉降曲线类似于“勺子”形,最大沉降位置在盾构开挖面前方5 m处,有建筑情况的沉降范围和沉降量均大于无建筑的情况。

The existing research mainly focuses on the stability of shield excavation face without building load on the surface.In practical engineering,there are often buildings near the shield excavation face,so it is necessary to consider the impact of adjacent building load on the shield excavation face.By establishing a 3D finite element model,the instability evolution characteristics of large diameter shield excavation face under surface building eccentric load in clay layer are studied.The research indicates:when the support ratio of the excavation face is 0.6–1.0,the surface buildings have little effect on the displacement of the excavation face;when the support ratio is less than 0.3,there is unbalanced building load on the surface,resulting in the increase of soil displacement in front of the shield excavation face,and the instability influence area is much larger than that without buildings;with the decrease of support ratio,the soil mass in front of the excavation face gradually settles,and the settlement curve is similar to the spoon shape,the maximum settlement is 5 m in front of the shield excavation face,and the settlement range and settlement with buildings are greater than those without buildings.