分别以柱孔和球孔扩张模拟桩身和桩端的贯入过程，采用可以考虑天然饱和黏土应力历史和应力各向异性的圆孔扩张解答描述桩周土体的应力状态，推导了饱和黏土地基中静压桩终压力的理论解，进而基于桩周孔压径向消散的固结解答，在考虑桩周土再固结过程中松弛效应的基础上，推导了沉桩结束后静压桩时变承载力的解答，建立了静压桩承载力时效性系数的理论表达式。通过离心模型和现场试验对所提的理论解答的正确性进行了验证，研究了天然饱和黏土中静压桩承载力的时效性。结果表明：沉桩结束后较短时间内静压桩承载力时效性是超孔压消散和土体触变恢复共同作用的结果，一定间歇期后超孔压消散成为承载力增长的主要原因。

Considering the stress history and initial stress anisotropy of natural saturated clay under K0-consolidated condition, a theoretical solution to the jacking force of pile was derived by modeling the pile shaft penetration process as the spherical and cylindrical cavity expansions, respectively. Then, based on the radial excess pore water dissipation after the pile installation, an analytical solution to the time-dependent bearing capacity of the jacked pile was derived by considering the relaxation effect of the soil around the pile during reconsolidation process. And the theoretical expression for the timeliness coefficient of jacked pile bearing capacity in K0-consolidated natural saturated clay was established. The validity of the present solution was verified by the centrifuge model test and field test respectively, and the time-dependent bearing capacity were discussed in detail. The results show that, the time-dependent bearing capacity within a short time after pile installation can be attributed to the combination of the excess pore water pressure dissipation and the thixotropy recovery of the surrounding soils. After a certain rest time, the dissipation of the excess pore water pressure is the main reason for the increase of the bearing capacity.