下穿既有道路浅埋暗挖隧道施工技术研究

Research on the Construction Technology of Shallow-buried Excavation Tunnel Underpass the Existing Road

新建铁路线交叉穿越既有公路线和铁路线的施工是隧道建设中的技术难点之一,因施工不当引起的路面变形甚至坍塌,将会导致巨大的经济损失和不良的社会影响.以新建赣深铁路林寨隧道为背景,结合隧道下穿S229省道的工程特点,采用有限元软件对该标段的开挖进行数值模拟,对隧道开挖下穿既有省道的相互影响进行分析研究,提出了林寨隧道下穿既有省道S229的三个施工方案.建立三维数值模型,对施工方案进行了详细的比选与优化,得出将掌子面施工至DK188+480前先将S229省道往大里程临时改移,改移距离为道路与隧道中心线交叉处最大改移距离约37 m,改移后道路与隧道平面并行段最近净距约5 m.通过现场监测数据与数值计算沉降值的对比分析可知,路面沉降值基本符合沉降规律,数值计算与现场监测的沉降数值略有差异,但基本吻合.也进一步验证了数值计算的可靠性及推荐方案的合理性.

The construction of new railway line crossing existing highway and railway line is one of the technical difficulties in tunnel construction.The pavement deformation and even collapse caused by improper construction will lead to huge economic loss and adverse social impact.In this paper,taking the linzhai tunnel of Jiangxi Shenzhen railway as the background,combined with the engineering characteristics of the tunnel underpass s229 provincial road,the finite element software is used to simulate the excavation of this bid section,and the interaction between tunnel excavation and existing provincial highway is analyzed and studied.Three construction schemes of Linzhai tunnel underpass the existing provincial highway S229 are proposed,three-dimensional numerical model is established,and the construction schemes are compared and optimized in detail.It is concluded that provincial highway S229 should be temporarily relocated to a large mileage before the construction of the tunnel face to DK188+480.The maximum relocation distance is about 37 meters at the intersection of the road and the tunnel center line,and the nearest net distance between the road and the tunnel plane parallel section is about 5 meters after the relocation.Through the comparison and analysis of the field monitoring data and the numerical calculation settlement value,it can be seen that the pavement settlement value basically conforms to the settlement law,and the different between the settlement value of numerical calculation and field monitoring is slightly,but it is basically consistent.The reliability of the numerical calculation and the rationality of the recommended scheme are further verified.