盾构隧道变位复变函数解的验证与参数分析

针对不排水黏土浅埋盾构隧道的一种(均匀)收敛-椭(卵)变(形)-(刚体)下沉复合体积损失模型,分别引入椭变系数与下沉系数,采用改进的复变函数求解方法,求解对应的地层变位和地层应力,并分析复合体积损失模型参数的影响。参数分析表明:(1)随着隧道下沉系数或椭变系数的增大,地表沉降值增大,沉降槽宽度也增大,但增加的量值不大;(2)隧道椭变系数主要会影响地层水平变位的大小及方向,而隧道下沉降系数则主要影响地层水平变位分布曲线的曲率;(3)最大环向应力出现在开挖边界的顶部,主因是隧道的下沉,次因是隧道的椭变。本文方法可以计算分析粘土浅埋盾构隧道开挖引起的地层变位以及应力分布。

Verification and Parameter Analysis for Complex Variables Solution of Deformation of Shield Tunnels

With regard to a composite model of (uniform) convergence-elliptical (oval) deformation-(rigid) sagging volume loss due to shallow shield tunneling, an oval-deformation coefficient and a sagging coefficient are introduced, and a complex variable method is adapted to express the displacement pattern of the excavation boundary, to find the corresponding solutions of ground displacements and stresses, and to analyze the effects of the model parameters. Based on sample calculations, the following observations can be made:(1) with the increase of the tunnel sagging ratio or oval deformation ratio, the ground surface settlement value and trough with slightly increases mainly in. (2) The tunnel oval deformation ratio mainly affects the size and direction of ground horizontal displacement, while the sagging ratio mainly affects the curvature of the distribution curve of ground horizontal displacement. (3) The maximum circumferential stress occurs at the top of the excavation boundary, mainly due to sagging of the tunnel and secondly due to oval deformation of the tunnel. The method in this paper can be used to calculate and analyze the distribution of deformation and stress of the ground caused by the excavation of the shallow shield tunnels in clays.