近距离平行隧道开挖的三维有限元数值分析

Three dimensional numerical analyses on the construction of two closely-spaced parallel tunnels

利用3D-σ有限元程序对近距离平行隧道的三种典型开挖方式进行了三维数值模拟;分析了在三种不同开挖方式下地面沉降槽形状及发展、土体和隧道的位移特征、岩体横向位移、衬砌内部应力;同时对相向同步开挖的各施工步进行了位移分析。数值分析结果表明,近距离平行隧道采用相向同步开挖对岩层扰动相对较小、地表及隧道位移量较低、衬砌时的应力较小。相向同步开挖与同向开挖时地表沉降槽的形状明显不同。

There are three options to construct two closely spaced parallel tunnels, namely, synchronous excavation in the same direction, asynchronous excavation in the same direction, excavation in opposite directions. Based on a three dimensional FE numerical model, the shape and development of the ground surface settlement trough, the subsidence characters of rock and tunnels, horizontal displacements in the rock mass as well as the stresses in the linings are analyzed. Displacements in each construction step of the excavation in opposite directions are also determined. Results of the numerical analyses indicate, for the construction of two closely spaced tunnels, the excavation in opposite directions is much better than the other two options.