浅埋顶管群下穿运营高铁施工地表变形研究

Research on Surface Deformation during Construction of Shallow-buried Pipe-jacking Group under High-speed Railway

为了研究下穿运营高铁顶管群施工过程中的地表变形情况,通过三维数值模拟及现场监测,研究下穿运营高铁顶管施工案例中的地表变形规律,并通过分析相关影响因素,提出地表沉降控制措施。研究表明:顶管施工过程中,3倍管径范围内地表变形受施工影响较明显,最大变形点发生在顶进断面顶管轴线位置,当距管轴线距离大于3倍管径时,地表沉降量逐渐收敛于零;横向沉降趋势呈“U”形分布,沉降量随着距顶进面距离增大而整体减小,但变形量分布形态基本保持不变。天窗施工期间,列车开通运行24 h后地表产生明显变形,列车运行48 h后地表变形基本趋于稳定。受管-土相互作用影响,地表沉降理论计算结果较数值模拟结果略小,建议复杂地层条件下微型顶管土压力计算优先选用太沙基理论。

In order to study the surface deformation during the construction of the pipe jacking group of the underpass high-speed railway,through three-dimensional numerical simulation and on-site monitoring,the surface deformation law in the case of the pipe jacking construction of the underpass high-speed railway is analyzed,and the surface subsidence control measures are proposed through the analysis of relevant influencing factors.The research shows that during the pipe jacking construction,the surface deformation within the 3 times the pipe diameter range is obviously affected by the construction,and the maximum deformation point occurs at the pipe jacking axis of the jacking section.When the distance from the pipe axis is greater than 3 times the pipe diameter,the surface settlement gradually converges to zero.The trend of lateral settlement is U-shaped,and the settlement decreases as the distance from the jacking surface increases,but the distribution of deformation remains basically unchanged.During the working time of closed section,the ground surface was significantly deformed after the train was opened for 24 hours,and the ground surface deformation basically stabilized after the train was operated for 48 hours.Due to the influence of pipe-soil interaction,the theoretical calculation results of surface settlement are slightly smaller than the numerical simulation results,and it is suggested that Terzaghi theory should be preferred for the calculation of soil pressure of micro-pipe jacking under complex formation conditions.