大型地下立交正交下穿段三维有限元数值分析

在大型互通式地下立交工程中,下穿隧道往往都处于整个地下立交工程的最低点,需要设置排水泵房,于是造成了在一定空间范围内的多洞室开挖。下穿隧道及排水泵房的修建不可避免地会对上覆小净距隧道产生影响,本文针对地下立交工程中隧道正交下穿段,以厦门东坪山地下立交工程为背景,采用三维有限元方法对新建下穿隧道的施工过程进行动态模拟,分析下穿段隧道动态开挖时,整个正交下穿段位移和变形的变化规律。计算结果表明：下穿隧道和排水泵房施工时整个下穿段将产生不均匀沉降、不均匀侧移和变形,需要对下穿段隧道和排水泵房所处的围岩进行加固,并在上覆隧道相应处设置防护钢拱架。

3D FE Numerical Analysis on Undercrossing Section of Underground Interchange

In the large-sized underground interchange,the undercrossing tunnel is always the lowest part in the whole project.Therefore,water pump house should be set up,which will result in multi-tunnel excavation.The construction process of the undercrossing section of Dongpingshan underground interchange in Xiamen is dynamically simulated by means of 3D finite element method and the rules of the displacement and deformation induced are analyzed.The calculation results show that differential settlement,differential lateral displacement and deformation will occur to the undercrossing section during the construction of the undercrossing tunnel and the water pump house,the rock mass of the undercrossing section and the water pump house should be reinforced and protective steel arches should be set up at the corresponding positions of the overlying tunnel.