框架逆作的超大深基坑立柱差异沉降可视化分析

Visualization and analysis of the differential-settlement between columns in a super-large deep excavation with frame-top-down method

软土地区采用框架逆作法施工超大深基坑工程,立柱桩与土体、框架梁支撑与施工栈桥的相互作用,所引起的立柱差异沉降需严格控制。结合工程实例,采集立柱沉降数据,研究可视化分析方法,绘制直观精确的平面图和三维曲面模型,详细分析了立柱差异沉降的时空效应特征。分析结果表明,立柱沉降在空间和时间上存在不均匀性,基本呈现上浮趋势,单根立柱最大回弹量较小,而立柱间差异沉降较大。基坑中部立柱变形大于边界立柱,坑内土体隆起为主要影响因素,栈桥对立柱隆起具有明显的约束作用。最大差异沉降发生于底板浇筑之前,且位于栈桥与塔楼的临界位置,与土方开挖顺序密切相关。及时分析和反馈可视化信息,有利于指导信息化施工,控制立柱差异沉降。

The differential-settlement between columns should be strictly controlled in a super-large deep excavation with frame-top-down method in soft soil area,considering the interaction of columns and the soil body, supports of the framework and construction trestles. Based on the engineering case, the characteristics of time-space effect of differential-settlement between columns have been fully analyzed by gathering the settlement data of columns,studying on a visualization analysis method,drawing a visualized accurate planar graph and 3D surface model. The research results show that the obvious uneven settlement of columns exists in space and time,which presents the overall rise tendency,the maximum rebound amount is smaller in individual column but differential-settlement between columns is bigger. The deformation of columns in the central part is bigger than alongside the boundary of the deep foundation pit,which mostly caused by soil heave of the pit and the obvious trestle restraining effect on column uplift. The biggest differential-settlement is located at the trestle critical position,which occurs before pouring concrete floor,and it is closely related with the excavation sequence. Timely analysis and feedback of visualization information can help to guide the information construction and control the differential-settlement between columns.