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结合北京某地铁车站基坑工程实际工程地质条件和水位地质条件,给出围护桩监测方案。通过对基坑工程西区中围护桩水平位移、钢支撑轴力的监测数据进行分析,得到了一些有价值的规律。结果表明:桩体水平位移能直接反应围护桩的变形特性,是基坑安全评价的重要指标。钢支撑对桩体变形有明显的限制作用,在钢支撑作用点处,桩体水平位移有明显的拐点,在两道钢支撑之间有个偏向基坑内凸曲线,开挖截止到基坑底部,围护桩变形最大的部位,位于最低两根钢支撑之间的凸曲线上,此点大概在基坑深度的2/3处。桩体最大水平位移随着土体开挖呈下降趋势,基坑开挖到底板时,基本稳定在基坑深度的2/3处。钢支撑轴力的变化与温度、土层性质、基坑开挖方式、速度和下层钢支撑的安装及拆除密切相关。
Combined with the actual engineering geological conditions and water level geological conditions of the foundation pit project of a metro station in Beijing, the monitoring scheme of the retaining pile is given. By analyzing the monitoring data of the horizontal displacement of the retaining pile and the axial force of the steel support in the west of the foundation pit project, some valuable laws were obtained. The results show that the horizontal displacement of the pile body can directly reflect the deformation characteristics of the retaining pile and is an important index of the safety evaluation of the foundation pit. The steel support has a significant limiting effect on the deformation of the pile body. At the point of steel support effect, the horizontal displacement of the pile body has a significant inflection point. There is a convex convex curve towards the foundation pit between the two steel supports, and the excavation ends up to the bottom of the foundation pit , The largest deformation of retaining pile site, located between the lowest two steel support convex curve, this point about 2/3 of the depth of the pit. The maximum horizontal displacement of piles is declining with the excavation of soil. When the foundation pit is dug to the bottom plate, it is basically stable at 2/3 of the depth of the foundation pit. The change of steel support axial force is closely related to the temperature, the nature of soil layer, the way of excavation of foundation pit, the speed and the installation and removal of lower steel support.