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温州350 m超高层中超长桩加载2800 t的试桩静载试验设计与分析表明:在地表土质承载力较低场地进行大吨位堆载试验时,可选择桩梁式堆载支墩-反力架装置来完成试验。对超长桩来说,在最大加载条件下,实测桩端阻力仅为桩顶荷载的25%左右,超长桩表现为端承摩擦桩性状。在使用荷载下,桩顶沉降的90%以上来自桩身压缩,在进行超长桩设计时,要充分考虑桩身质量对试桩沉降的影响。同时,桩底沉渣清除的干净与否,也直接影响超长桩的沉降。超长桩桩侧上部土层摩阻力具有不同程度的软化现象,而中下部土层侧摩阻力具有较弱的强化效应,因此在超长桩承载力计算时,不同深度土层的桩侧阻力和桩端阻力都应乘以相应不同的修正系数。试验结果显示淤泥土、淤泥质黏土、淤泥夹粉砂土中极限侧阻充分发挥所需的桩土相对位移阀值分别约为5～7 mm、6～8 mm和8～10 mm。
The design and analysis of the static load test of 350 m super high-rise medium-long pile in 2800t load in Wenzhou shows that when large-tonnage heap load test is carried out in the site with low soil-surface bearing capacity, the pile- Rack device to complete the test. For the super-long pile, under the maximum loading condition, the measured pile end resistance is only about 25% of the pile top load, and the long pile shows the end bearing friction pile. Under the service load, more than 90% of the settlement of the top of the pile comes from the compression of the pile body. When designing the extra-long pile, the influence of the pile mass on the test pile settlement should be fully considered. At the same time, clean the pile bottom sediment or not, but also directly affect the settlement of super-long pile. The friction of upper soil layer over the long pile has different degrees of softening, while the lateral friction of the middle and lower soil layers has weaker strengthening effect. Therefore, when calculating the bearing capacity of the super-long pile, the pile lateral resistance And pile end resistance should be multiplied by the corresponding different correction factor. The results show that the relative displacement threshold of pile-soil required for full exertion of ultimate lateral resistance of silt, silt clay and silt silt is about 5-7 mm, 6-8 mm and 8-10 mm, respectively.