下穿输水隧道对北京地铁五棵松站的影响之数值分析

2条平行暗挖输水隧道从北京地铁五棵松站下方穿过，2条隧道中心间距为94 m，隧道毛洞顶部距离车站底板仅3717 m，属于近接施工问题。为了确保输水隧道施工时，地铁车站结构及轨道的安全，采用三维有限元仿真分析的方法对输水隧道开挖全过程进行模拟。通过对地表位移和车站顶、底板位移随开挖过程变化规律进行计算分析，得出需要对输水隧道扩大段、注浆通道和下穿隧道周围的土体进行注浆加固，才能确保地表和轨道位移不超过规范所规定的限值，并提出为了降低施工过程中，地铁车站两侧因不均匀沉降而产生的扭矩，需要在车站两侧采用对称施工的建议。

Numerical Analysis on Influence of Construction of Water Conveyance Tunnels Crossing Underneath Existing Wukesong Metro Station

Twin parallel mined water conveyance tunnels cross underneath existing Wukesong Metro station.The centerto-center distance between the twin tunnels is 9.4 m and the distance between the crown of the twin water conveyance tunnels and the floor of the Metro station is 3.717 m.Therefore,the twin water conveyance tunnels will be excavated in close proximity to the existing Metro station.In the paper,the full course of the excavation of the twin water conveyance tunnels is simulated by means of 3D finite element method,so as to ensure the safety of the existing Metro station and tracks during the excavation of the twin water conveyance tunnels.The analysis on the trend of the displacement of the ground surface and the roof and floor of the existing Metro station demonstrates that the enlarged section of the water conveyance tunnels,the grouting tunnel and the soil mass surrounding the water conveyance tunnels should be reinforced by means of grouting,so as to constrain the displacement of the ground surface and the Metro rails under the specified limits.It is also proposed that symmetrical construction should be carried out on both sides of the Metro station so as to minimize the torque on both sides of the Metro station caused by differential settlement.