浅埋小间距隧道开挖围岩变形及控制对策

采用FLAC软件对地表有相对硬壳层的粉沙层中隧道开挖之后地层的变形机理进行模拟，通过分析隧道开挖后围岩变形的空间效应特性曲线，确定隧道开挖支护后引起的围岩变形的幅度和范围，找出隧道开挖最不利荷载工况和结构薄弱部位，为施工方案提供理论依据和决策支持。研究表明，不同的施工顺序引发不同的施工力学状态，进而引起不同的施工力学效应，隧道开挖先后顺序不同对围岩区域、幅度的扰动也不同。以北京地铁某车站的实测为基础，分析了粉沙地层中隧道施工不同工序引起的各部分变形情况，进而提出了相应的工程措施。

Ground Deformations Caused by Excavation of Shallow-buried Tunnels with Small Spacing and Their Countermeasures

FLAC software is used to simulate the mechanisms of the ground deformations caused by tunnel excavation in silty sand layers where there exists hard shell on the ground surface. By means of analyzing on the characteristic curves of the spatial effects of the ground deformations caused by the tunnel excavation, the amplitude and scope of the ground deformations caused by the excavation and reinforcement of the tunnels are determined and the most adverse loading conditions of the tunnel excavation and the weak positions of the structures are obtained, which provides theoretical basis and decision-making support for the selection of the construction alternatives. The study indicates that different construction sequences lead to different construction mechanical states, which in turn lead to different construction mechanical effects. Furthermore, different construction sequences lead to different disturbance areas and different disturbance amplitudes. On basis of the measurement data of a station of Beijing Metro, the article analyses on the ground deformations caused by tunnel construction in silty sand layers and recommends some countermeasures for the ground deformations.