基于有效应力法的静压桩时变承载力研究

基于天然饱和黏土地基中静压沉桩扩孔问题的弹塑性解，以沉桩结束后桩周土体的应力状态为初始条件,推导了桩周孔压消散的解析解。在此基础上，考虑桩周土体再固结过程中的土体松弛效应，提出了采用有效应力计算天然饱和黏土中静压桩时变承载力的理论方法。通过已有离心模型试验和现场试验结果对该方法进行了验证，研究了沉桩结束后静压桩承载力随固结时间的变化规律。结果表明，提出的理论方法合理考虑了土体的原位力学特性、沉桩效应及沉桩结束后土体有效应力的变化，因而可以较好地预测静压桩的时变承载力。该研究成果为合理确定黏土中静压桩承载力提供了理论依据，具有一定的理论和工程意义。

Time-dependent bearing capacity of a jacked pile based on the effective stress method

Based on the elasto-plastic solution to the cavity expansion for jacked piles problems in natural saturated clay, an analytical solution to the excess pore water dissipation around the pile is derived with aid of the stress state of the soil immediately after pile installation. On this basis, a theoretical method for calculating the time-dependent bearing capacity of the jacked pile in natural saturated soil is presented by considering the soil relaxation effects on the soil around the pile during reconsolidation of the soil. The theoretical method is verified by the published centrifuge model test and field test respectively, and the variation of the bearing capacity of the jacked pile with consolidation time is studied in detail. The results show that the proposed theoretical method can be applied to reasonably predict the time-depended bearing capacity of the jacked pile, because the in-situ mechanical property of the soil, the installation effect, as well as the reconsolidation effect after installation are properly considered by the proposed method. The results of this paper have great theoretical significance in proper determining the bearing capacity of a jacked pile in clay.