新疆地铁一号线王家梁站洞桩法施工数值模拟研究

Numerical Simulation Study on PBA Excavation at Wangjialiang Station of Xinjiang Metro Line 1

以新疆地铁一号线王家梁站为工程背景,通过CAD-Rhinocero-Kubrix方式建立计算模型,应用Flac3D软件模拟洞桩法施工,对地层位移变化等进行研究,并优化导洞施工方案。分析表明:导洞开挖与扣拱施工是引起地表沉降的两个主要阶段,二者引起地表沉降比例高达近90%,导洞与车站拱顶超前注浆加固非常有必要;已有现场测量数据与数值计算结果吻合度较高,验证了模拟结果的正确性,基于此对后续施工引起地表沉降值做出预测;洞桩法施工对周围地层造成多次扰动,但扰动范围较小,中柱是主要的受力结构,施工中应重点监测;通过对比分析,确立了先中后边、先上后下的最优导洞开挖方案。

Based on the engineering background of Wangjialiang Station in Xinjiang Metro Line 1, the calculation model was established by CAD-Rhinocero-Kubrix. The Flac^3D software was used to simulate the construction of PBA method and the displacement of the surrounding strata was studied. In addition, the optimization of different pilot tunnel excavation schemes was carried out. The results showed that the pilot tunnel excavation and the arching were two main stages which resulted in the total subsidence, and the proportion of the surface subsidence could reach up to nearly 90%. It was necessary to strengthen the pilot tunnel and the station vault with advanced grouting scheme. The existing field measurement data were in good agreement with the numerical simulation results, so the correctness of the numerical results was verified. Based on the numerical results, the surface subsidence induced by subsequent construction was predicted. The construction of PBA （pile-beam-arch） method had caused repetitious disturbances to surrounding strata, but the disturbance range was small. The middle pile was the main force structure, and it should be monitored more frequently. By comparative analysis, the optimal excavation scheme of pilot tunnel is determined. In horizontal direction, it is better to excavate the middle pilot tunnel ahead of the side one, while in vertical direction, it is better to excavate the upper pilot tunnel ahead of the bottom one.