隧道明暗挖分界面处基坑支护桩施工力学效应

论文以重庆某轻轨车站区间隧道明暗挖工程为例,提出隧道明暗挖分界面处支护桩结构的物理概化模型,采用数值模拟并结合现场监测结果,对隧道明暗挖分界面处基坑支护桩施工力学效应进行研究。分析结果表明:支护桩桩间距、桩截面尺寸、桩截面形状对支护桩力学效应的影响中,桩截面尺寸对支护桩桩身变形及力学效应影响最为显著;隧道洞径、埋深及走向变化对支护桩力学效应的影响中,洞径对支护桩变形影响较大;先开挖隧道后开挖基坑能有效减少坡顶沉降及侧向位移,同时桩身弯矩剪力值也较小;支护桩施工后设置拱形连梁可以有效增强余桩的支护作用。

Study on Mechanical Effect of Support Pile at the Interface between Open and Subsurface Excavation

This paper proposed an interval tunnel dug at the interface of the physical shading supporting pile structure model, taking an open and subsurface excavation project of the railway station in Chongqing as an example, the numerical simulation and combined with the on-site monitoring results were used to study the mechanical effects of foundation pit support piles at the tunnel interface. The analysis results show that considering the influence of the spacing of retaining piles, the size of pile cross section and the shape of pile cross section on the mechanical effect of retaining piles, the size of pile cross section has the most significant effect; considering the influence of tunnel diameter, buried depth and direction on the mechanical effect of supporting piles, the results show that the diameter of tunnel has a great influence. The settlement of slope top and lateral displacement can be effectively reduced by excavating tunnel first and then excavating foundation pit, and the bending moment and shear force of pile body are also small. The arch connecting beam can effectively enhance the supporting effect of remaining piles after the construction of cut off piles.