深基坑变形规律现场监测

给出了北京地铁某车站深基坑围护和变形监测方案,对基坑变形规律进行了现场监测研究,重点分析了基坑的水平变形、锚索内力和钢支撑轴力变化规律。结果表明,基坑开挖的深度与无支撑暴露的时间对围护桩的变形、锚索内力及钢支撑的轴力影响较大。随着基坑开挖深度的增加和钢支撑的施加,围护桩的变形形态由向坑内的前倾型曲线逐渐变为弓形。围护桩的水平位移、钢支撑的轴力也随着基坑开挖深度的增加而增大。随着钢支撑的施加,围护桩水平位移及锚索内力都趋于稳定,说明钢支撑、围护桩和预应力锚索联合支护形式能够有效地控制基坑变形,保证地铁车站安全施工。

In-situ monitoring on deformation laws of deep foundation pit

The supporting plan and deformation monitoring plan are given and the in-situ monitoring study is completed on the foundation pit deformation,especially on the horizontal deformation of the foundation pit,the axial force of anchorage cable and the steel support.The result shows that the excavation depth and the exposed time without support of the foundation pit affect much on the deformation of the retaining piles,the tension force of the cables and the axial force of steel support.With the increment of excavation depth and the application of steel support,the deformation state of the retaining piles gradually develops from the anteverted curve towards foundation pit to bow curve.The horizontal deformation of the retaining piles and the axial force of the steel support increase with the increment of excavation depth.With the application of steel support,the horizontal deformation of the retaining piles and the tension force of cables become steady.The multiplex supporting plan consists of steel support,retaining piles and pre-stressed anchorage cable can control the deformation efficiently and assure a safe construction of subway station.