盾构掘进地面沉降虚拟镜像算法

盾构掘进所致地面沉降的准确预估,对于邻近建（构）筑物的保护至关重要。假定土体为均质各向同性半无限空间不可压缩弹性体,基于虚拟镜像技术,推导了在隧道边界土层不同收敛模式下的地面沉降计算公式,计算结果比数值积分算法更接近实测。由于实际土体具有各向异性、成层性和可压缩性,本文算法与数值积分算法均高估了横向地面沉降槽宽度。引入沉降槽宽度修正参数对理论公式进行修正,修正算法计算结果更符合实际,可简单可靠地估算盾构隧道施工地层损失引起的地面沉降。

Estimation of shield tunnelling-induced ground surface settlements by virtual image technique

The accurate estimation of ground surface subsidence induced by shield tunnelling is crucial to the protection of buildings or structures in the vicinity. Under the hypothesis that the soil is a homogeneous isotropic incompressible linear-elastic semi-infinite half-space, equations for calculation of tunnelling-induced ground surface settlements under different surrounding soil intrusion models are derived based on the virtual image technique. Compared with those of numerical integration methods, the predicted results by the proposed method are more accurate. For the soil in reality is anisotropic, layered and compressible, the transverse ground surface settlement trough width is over-estimated both by this study and the numerical integration method. A modification parameter of trough width is introduced into the deduced formula. The modified method is proved by the field observations to be an easy and reliable method for prediction of ground surface settlements resulting from ground loss during construction of shield-driven tunnels.