全螺纹钻(挤)孔灌注桩在上海软土地区的应用

Application of drilled screw piles in Shanghai soft soils

通过全螺纹钻(挤)孔灌注桩在上海世博村Ⅰ地块工程上的应用说明其在上海软土地区的适用性。首先根据现有施工条件提出了钻孔灌注桩和全螺纹钻(挤)孔灌注桩两种桩基方案,并利用已有单桩承载力计算公式分别对两设计方案中的单桩进行极限承载力预估。预估结果表明全螺纹钻(挤)孔灌注桩的单桩极限承载力约为钻孔灌注桩的1.47倍。之后对全螺纹钻(挤)孔灌注桩进行低应变动力测试和单桩静载荷试验。低应变动力测试结果表明全螺纹钻(挤)孔灌注桩在上海软土地区成桩质量可靠;单桩静载荷试验结果表明全螺纹钻(挤)孔灌注桩承载力较高,并且与预估值比较接近,说明了本文采用的单桩承载力计算公式的准确性。最终通过方案比选,选用全螺纹钻(挤)孔灌注桩作为工程桩且应用效果良好。

The applicability of drilled screw pile in Shanghai soft soils is proved by the Expo Village(Block Ⅰ) project. Firstly, two design schemes, i.e., traditional drilled pile and drilled screw pile, are put forward according to the existing construction conditions. The bearing capacities of the two types of piles are predicted using the existing calculation methods. The predicted results show that the ultimate capacity of the drilled screw pile is 1.47 times larger than that of the traditional drilled pile. Then low-strain dynamic tests and static load tests are conducted on this type of pile. The result of the low-strain dynamic tests shows that the pile quality of the drilled screw pile is very reliable in Shanghai soft soils. The results of the static load tests demonstrate that the designed drilled screw pile has a high bearing capacity which is close to the predicted value, and the accuracy of the proposed method is validated. Finally by the scheme comparison, the drilled screw pile is chosen as the engineering pile of this project, and its application effect is good.