北京地铁7号线达官营站八导洞开挖方案对比研究

Excavation Schemes for Eight Pilot Tunnels in the Daguanying Subway Station on Beijing Metro Line 7

北京地铁7号线达官营站开挖断面大,土质情况复杂,地下管线众多,地表为车流量大的广安大街且近距离下穿人行过街天桥。为了确保车站暗挖施工安全及市政设施正常运行,文章采用FLAC3D软件,建立了达官营车站导洞模型,对导洞不同开挖方案进行了对比研究。研究结果表明,先进行上部小导洞开挖比先进行下部小导洞开挖导致的拱顶、管线及地表沉降都小,衬砌受力更合理。因此,选择了先进行上部小导洞开挖的方案。在小导洞开挖过程中进行了导洞拱顶、管线及地表沉降的动态监测,监测结果与数值模拟结果较为一致,进一步验证了所采取的开挖方案的合理性,也表明利用数值分析方法预测沉降是可行的。

The construction of the Daguanying subway station on Beijing Metro Line 7—beneath heavy traffic on Guangan Avenue and adjacent to a pedestrian overpass—features a large excavation cross section, complex soil conditions and numerous underground utilities. In order to guarantee safe construction and normal operation of municipal infrastructure, FLAD3 Dsoftware was used to establish a model for the pilot tunnels and a comparison study of the excavation schemes for the pilot tunnels was carried out. The results indicate that the settlements at the crown, utilities and ground induced by excavation of the upper pilot tunnel first were less than those induced when excavation of the lower pilot tunnel occurred first; the stress distribution on the lining was also more reasonable for the former, so the scheme of excavating the upper pilot tunnel first was selected. Dynamic monitoring of the settlements at the crown, utilities and ground was carried out during excavation of the pilot tunnels and the real-time monitoring results are nearly consistent with those of numerical simulation, which indicates the rationality and feasibility of this numerical analysis.