矿山法地铁区间隧道切桩密接下穿既有地铁车站的施工沉降监测及控制措施

Construction Settlement Monitoring and Control Measures for Mining Method Tunnel Section by Cutting Piles Closely Under-passing Existing Metro Station

[目的]地铁区间隧道切桩密接下穿既有地铁车站时,对上部车站变形影响较大,为了确保施工的安全性,需要采取有效措施控制地铁车站沉降。[方法]依托某区间隧道下穿既有地铁车站工程,建立三维数值模型,分析不采取沉降控制措施直接切桩下穿时的车站沉降,研究了增设临时仰拱、错距开挖以及注浆加固等措施的沉降控制效果。提出了多措施组合控制方案,并采用实测的沉降监测数据验证了组合沉降控制方案的可行性。[结果及结论]研究结果表明,不采用控制措施直接下穿地铁车站时,车站最大沉降超过规定限值。注浆加固措施的沉降控制效果最优,沉降减小率为57.3%;增设临时仰拱次之,沉降减小率为40.4%;错距开挖效果最差,沉降减小率为20.8%。多措施组合施工方案,可以满足沉降限值。实测的沉降监测数据显示,多措施组合控制方案能有效控制施工沉降。

[Objective]When the sectional tunnel closely under-passes the existing metro station by cutting piles,it has a significant impact on the deformation of the upper station.In order to ensure the safety of construction,it is necessary to take effective measures to control the settlement of metro station.[Method]Based on the project of a sectional tunnel under-passing the existing metro station,a three-dimensional numerical model is established to analyze the station settlement when being under-passed by cutting piles without settlement control measures.The settlement control effects with measures such as addition of temporary inverted arches,staggered excavation,and grouting reinforcement are studied.A multiple measure combination control scheme is proposed,and its feasibility is verified by the measured engineering data.[Result&Conclusion]The research results indicate that when the tunnel underpasses the station directly by cutting piles without taking settlement control measures,the maximum settlement of the station will exceed the specified limit.The grouting reinforcement produces the best effect on settlement control with the settlement being reduced by 57.3%.Addition of temporary inverted arches follows next by 40.4%,and staggered excavation has the least effect by 20.8%.The settlement limit can be met by using the multiple measure combination control scheme,which is verified to be feasible by the monitoring data,and can provide reference for similar projects.