地铁车站不同施工方案比选研究

Comparison and selection of different construction schemes for subway stations

与传统浅埋暗挖法对比,横向盖洞法对对最小覆土厚度无特殊要求,解决了超浅埋车站暗挖施工问题。为深入探讨横向洞盖法与传统PBA工法的区别,文章以济南某换乘站为研究对象,介绍了两种工艺的施工工序,通过有限元软件建立两种工艺的数值模型,对比了横向洞盖法与PBA工法施工全过程的沉降规律,并系统探讨了顶管刚度、顶进范围等参数的影响规律。研究结果表明:和PBA工法相比,横向洞盖法有着施工精度高、工作面多且大、造价低、速度快、受力合理、传力清晰等优点;两种工法在整个导洞开挖时的沉降分别占总沉降的87.4%和75.6%,是地表沉降控制的重点;横向洞盖法的地表整体沉降小于PBA工法,且当顶班覆土深度在7m以内时,横向洞盖法对控制地表沉降有明显优势,故对于本项目顶(板覆土深度约为3.9~4.4m),横向洞盖法更加合适;从整体来看,改变横向洞盖法中钢管外径不会对施工阶段的地表沉降造成较大的影响,随着钢管外径的改变,地表沉降波动范围为0~2mm;地表沉降在提高侧向顶进距离时表现出先快速增大后趋于稳定的规律。

Compared with the traditional shallow buried underground excavation method,the horizontal cover hole method has no special requirements for the minimum soil cover thickness,solving the problem of underground excavation construction in ultra shallow buried stations.In order to deeply explore the differences between the transverse tunnel cover method and the traditional PBA construction method,a transfer station in Jinan is taken as the research object.Firstly,the construction processes of the two processes are elaborated,and then numerical models of the two processes are established using finite element software.The settlement laws of the entire construction process of the transverse tunnel cover method and the PBA construction method are compared.And the influence laws of parameters such as pipe jacking stiffness and jacking range were systematically explored.The research results indicate that compared with the PBA construction method,the transverse tunnel cover method has advantages such as high construction accuracy,multiple and large working faces,low cost,fast speed,reasonable stress,and clear force transmission;The settlement of the two construction methods during the excavation of the entire pilot tunnel accounts for 87.4%and 75.6%of the total settlement,respectively,making them the focus of surface settlement control;The overall surface settlement of the horizontal tunnel cover method is smaller than that of the PBA construction method,and when the top cover soil depth is within 7 m,the horizontal tunnel cover method has obvious advantages in controlling surface settlement.Therefore,for the top of this project(with a soil cover depth of about 3.9~4.4 m),the horizontal tunnel cover method is more suitable;Overall,changing the outer diameter of the steel pipe in the horizontal tunnel cover method will not have a significant impact on surface settlement during the construction phase.As the outer diameter of the steel pipe changes,the fluctuation range of surface settlement is 0~2 mm;When increasing the lateral jacking distance,surface subsidence exhibits a pattern of first rapidly increasing and then stabilizing.