中文摘要：

天然饱和黏土中静压桩沉桩结束后其桩周土体逐渐固结,由于旧桩周围土体已完全固结,其桩周土体的力学特性与新桩有显著差异,承载特性亦有较大区别。针对新、旧桩单桩的荷载–沉降特性,在考虑土体初始各向异性、沉桩效应的基础上,基于柱孔不排水扩张后桩周土体应力与孔压基本解答,研究新、旧桩周土体力学特性的差异。在此基础上,根据新、旧桩周土体的力学特性和桩侧土体在加载过程中的力学特性,提出分别适用于新桩与旧桩的荷载传递模型,并通过与现场试验结果对比进行验证。研究结果表明,该荷载传递模型能较好地预测新、旧桩的荷载–沉降关系,对新、旧桩混合桩基承载机制的深化认识及其优化设计理论的完善都具有重要意义。

英文摘要：

Due to the reconsolidation after pile installation, mechanical properties of soil around old piles are extremely different from soil around new piles. Considering pile-jacking influence and initial anisotropy properties of the natural clay and adopting an analytical solution to elastoplastic cavity expansion due to the pile jacking-in, the mechanical characteristics of soil around the new and old piles are subsequently analyzed in detail. On this basis, load transfer models are proposed for new and old piles respectively according to the different mechanical properties in this paper. The theoretical solution is verified by the field test, and the results show that the presented methods predicted accurately the load-settlement relationship of the new and old piles.