沉桩方式及桩型对湛江组结构性黏土中单桩承载力时效性的影响

北部湾沿岸地区湛江组结构性黏土具有触变性,导致该土层中桩基时效性明显,不同沉桩方式及桩型的模型单桩对湛江组结构性黏土中桩基承载力时效性影响显著。以湛江组结构性黏土为地基,设计不同沉桩方式、桩型的模型单桩进行桩基静载实验,并对1倍桩径范围内桩周土的孔隙水压力进行监测。得到不同沉桩方式、不同桩型的模型单桩承载力及桩周土的孔隙水压力随休止时间的变化规律。结果显示：1)湛江组结构性黏土中单桩竖向极限承载力均随休止时间的增加而逐渐增大,且单桩竖向极限承载力增大的速率表现为前期增长快,后期增长慢；2)孔隙水压力消散规律与单桩竖向极限承载力增长规律基本吻合；3)湛江组结构性黏土中单桩承载力时效性可以用经验公式表述,在同一均质土层中不同沉桩方式、不同桩型的承载力时效性采用不同的时效性相关系数计算；4)不同沉桩方式对单桩承载力时效性影响差别较大,当桩型相同时,静压桩的竖向极限承载力增大的速率和幅度比振动桩大。5)单桩竖向极限承载力时效性与桩型有关,当沉入方式相同时,圆桩的竖向极限承载力增大的速率和幅度最大,管桩次之,方桩最小；

Influence of Pile Sinking Mode and Pile Type on Bearing Capacity and Timeliness of Single Pile in Structural Clay of Zhanjiang Formation

: The structural clay of Zhanjiang formation in the coastal area of Beibu bay has thixotropy, which leads to the obvious timeliness of pile foundation in this soil layer. The bearing capacity timeliness of the pile foundation in the structural clay of Zhanjiang formation is significantly affected by the model pile of different pile sinking methods and pile types. With the structural clay of Zhanjiang formation as the foundation, model single pile with different pile sinking methods and pile types was designed for static load test of pile foundation, and the pore water pressure of soil around the pile was monitored within the range of one pile diameter. The model bearing capacity of single pile and pore water pressure of soil around the pile vary with resting time were obtained. The results showed that: 1) the vertical ultimate bearing capacity of single pile in the structural clay of Zhanjiang group increased gradually with the increase of resting time, and the rate of the vertical ultimate bearing capacity of single pile increased rapidly in the early stage and slowly in the later stage.2) the dissipation law of pore water pressure is basically consistent with the growth law of vertical ultimate bearing capacity of single pile;3) the time-effectiveness of bearing capacity of single pile in the structural clay of Zhanjiang formation can be expressed by empirical formula, and the time-effectiveness correlation coefficient of bearing capacity of different pile sinking methods and pile types in the same homogeneous soil layer is different Calculation;4) the influence of different pile sinking methods on the timeliness of bearing capacity of single pile varies greatly. When the pile type is the same, the vertical ultimate bearing capacity of static pile increases at a higher rate and amplitude than that of vibrating pile.5) the timeliness of vertical ultimate bearing capacity of single pile is related to pile type. When the sinking mode is the same, the vertical ultimate bearing capacity of circular pile increases at the maximum rate and amplitude, followed by pipe pile and square pile at the minimum.