砂卵石地层中PBA工法导洞开挖顺序对地表沉降的影响

摘要

The station construction process with PBA method in sand gravel stratum was simulated by using finite element software ABAQUS,and the influence of different excavation sequence of pilot tunnels on surface subsidence was compared and analyzed by combing with field measured data.The results show that the underground excavation of station has no significant effect on the final surface subsidence by applying different excavation sequence of pilot tunnels,there is little difference between surface subsidence caused by first excavation of 1,3 pilot tunnels and that caused by first excavation of 2,4 pilot tunnels in the condition of first excavation of the lower pilot tunnels,the surface subsidence caused by first excavation of middle pilot tunnels is larger than that caused by first excavation of both sides of the pilot tunnels,and there is little difference among surface subsidence troughs caused by different excavation sequence of pilot tunnels at the end of pilot tunnel construction.%运用有限元软件ABAQUS对砂卵石地层中PBA工法车站施工过程进行数值模拟,结合现场实测数据,对比分析不同的导洞开挖顺序对地表沉降的影响.结果表明:采用不同的导洞开挖顺序暗挖地铁车站对地表最终沉降值无较大影响;在先行开挖下层导洞的情况下,先行开挖1,3导洞引起的地表沉降与先行开挖2,4导洞引起的沉降差异较小,但先行开挖中部导洞较先行开挖两侧导洞引起的地表沉降大;不同的导洞开挖顺序引起的地表沉降槽在导洞施工完毕时差异较小.