盾构隧道在不同施工工况中地表变形的模拟研究

Simulation Calculation on Shield Tunnel under Different Construction Conditions

为研究盾构隧道在不同施工工况中地表及自身的变形规律,本文建立了盾构隧道的有限元模型,对盾构隧道在不同施工工况下的开挖进行了模拟计算,即采用不同掘进顶推力施工时的地表沉降、隧道不同埋深情况下施工时地表沉降、开挖完成后地表作用大面积荷载情况下的地表沉降,以及隧道修建完成后地下水位变化后对盾构隧道变形等不同工况的模拟计算.结果表明:盾构的顶推力会导致其前方一定范围的地表土发生向上的隆起,并且顶推力越大,隆起变形和范围均较大.在相同顶推力作用下,埋深较大的隧道地表点的隆起变形和范围较小.地下水位上升会导致地表浅层土体发生回弹变形,并且下方有盾构隧道的地表的回弹值要比下方没有盾构隧道的地表的回弹值小;当地下水位从盾构隧道拱底逐渐升高到中心处和拱顶时,盾构隧道结构会出现竖向和侧向变形,并且水位越高,变形量也越大.

In order to study the influence on surface deformation of shield tunnel in different construction schemes, this paper simulates the following several aspects on the basis of establishing the finite element model of shield tun- nel. Which include surface settlement due to excavation under different driving thrust force and different buried depth of tunnel, surface settlement under large - area load after excavation and the influence on shield tunnel de- formation of underground water level changes after the tunnel construction completed. The result shows that shield thrust force will lead to the front range of surface soil uplifted and the thrust force is larger, uplift deformation and range are bigger. Under the same thrust force, uplift deformation and range of deeply buried tunnel surface are smal- ler. The rise of ground water level will lead to rebound deformation of the shallow layer soil and the surface rebound value of shield tunnel beneath the ground is smaller than no shield tunnel beneath the ground. When ground water level from the arch bottom of shield tunnel increased to the central place and vault place gradually, shield tunnel structure will appear displacement and lateral displacement, and the higher the water level, the greater the displace- ment value.