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考虑天然饱和黏土的应力历史和初始应力各向异性,推导得出了静压沉桩过程和再固结过程中静压桩周土体应力状态的变化规律。在此基础上,根据静压桩承载时桩侧土体应力状态与单剪试验及三轴试验中土体应力状态之间的相关性,基于总应力法推导了天然饱和黏土地层中静压桩时变承载力的解析解,提出了桩侧和桩端承载系数的理论计算方法。采用离心模型试验对本文解答进行验证,研究了沉桩结束后静压桩承载力随再固结时间的变化规律,分析了土体原位力学特性与静压桩承载系数之间的关系。研究结果表明,沉桩结束后静压桩承载力的增长主要是由于桩侧承载力的增长,而且静压桩承载力在沉桩结束后较短时间内增加的幅度较大,随后增长幅度变缓并趋于稳定;土体超固结比和静止侧压力系数越大,沉桩结束后承载力增长速率越快,但桩侧和桩端承载系数均随土体超固结比和静止侧压力系数的增大而减小。
Considering the stress history and the initial stress anisotropy of natural saturated clays, the variation regularity of the stress state of the soil around the jacked piles during the process of static pressure pile sinking and re-consolidation is deduced. On this basis, according to the correlation between the stress state of pile body and the stress state of soil in the triaxial test, the static pressure pile in natural saturated clay stratum is deduced based on the total stress method The analytical solution of the time-dependent bearing capacity is proposed. The theoretical calculation method of the bearing coefficient of pile-side and pile-end is proposed. The centrifuge model test is used to verify the solution in this paper. The variation regularity of bearing capacity of static pressure pile with reconsolidation time after pile sinking is studied, and the relationship between the mechanical properties of pile and the bearing coefficient of static pile is analyzed. The results show that the increase of bearing capacity of static pressure pile after pile driving is mainly due to the increase of bearing capacity of pile, and the bearing capacity of jacking pile increases more in a short time after pile driving, And the stability tends to be stable. The greater the over consolidation ratio and the rest pressure coefficient are, the faster the bearing capacity increases at the end of pile sinking. However, The pressure coefficient increases and decreases.