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本文从南通市沉入粉砂地基的四根预制短桩荷载试验资料中,着重对桩身应力量测数据、桩的荷载传递性能、锤击沉桩和水冲沉桩的特性、桩身进入粉砂层不同深度以及加载方法对单桩承载力的影响等进行分析和研究。试验结果表明:(1)沉入中密粉砂的桩侧摩阻力主要集中在桩尖以上7倍桩径范围内;(2)水冲法下沉短桩,其承载力显著降低,在粉砂地基中宜慎重采用;(3)桩尖进入中密粉砂不同深度时,其单桩承载力增长较大,用锤击法沉桩的增长率为130kN/m;(4)同一试桩先后进行慢速维持荷载法和快速维持荷载法试验,普遍有后一次试验所得的单桩承载力比前一次试验所得的要偏大一级荷载;在同一地区另一工程试桩中,先进行快速试验、后进行慢速试验,也有后一次试验结果较前一次试验结果偏大一级荷载的现象。
This paper focuses on the test data of four precast short piles submerged into silt foundation in Nantong City, focusing on the stress measurement data of the pile body, the load transfer performance of piles, the characteristics of hammered piles and water piles, and the entry of piles. The influence of different depths of silt layers and loading methods on the bearing capacity of a single pile was analyzed and studied. The test results show that: (1) The frictional resistance of piles sinking into medium dense silt sand is mainly concentrated in the 7-fold pile diameter range above the pile tip; (2) The water-sinking method sinks short piles and its bearing capacity is significantly reduced in the powder. The sand foundation should be carefully adopted; (3) When the pile tip enters the middle dense silt sand at different depths, the bearing capacity of the single pile grows larger, the growth rate of the hammer pile is 130kN/m; (4) The same test pile The slow maintenance load method and the rapid maintenance load method test were conducted successively. Generally, the load capacity of a single pile obtained from the latter test was larger than the one obtained from the previous test; in the test pile of another project in the same area, Rapid test, followed by slow test, there is also a phenomenon that the result of the previous test is larger than the result of the previous test.