饱和黏土中静压桩桩周土体强度时效性分析

发布时间：2018-01-23 13:04

本文关键词： 各向异性 K-MCC模型孔压土体强度离心机模型试验　出处：《哈尔滨工业大学学报》2016年12期 　论文类型：期刊论文

【摘要】：天然饱和黏土中静压桩在沉桩过程中对土体造成巨大的挤压,致使桩周土体产生较高的超孔隙水压力,沉桩结束后随着桩周土体的逐渐固结,土体强度表现出明显的时效性.为研究饱和黏土中静压桩沉桩后桩周土体强度的变化规律,基于K0-MCC模型并考虑了土体初始各向异性与诱发各向异性对桩周土体强度的影响,推导出柱孔不排水扩张后桩周土体应力及超孔压的解答,并根据轴对称固结理论推导了静压桩桩周孔压消散的理论解答.在此基础上,考虑桩周土体在固结过程中的松弛效应,对沉桩结束后桩周土体强度的时变效应进行了解析,并通过离心机模型试验验证了该解答的合理性.结果表明,该解答能够较为合理地预测沉桩结束后桩周土体强度与超孔压的变化规律,而土体超固结比、静止侧压力系数和土体有效内摩擦角等因素对桩周土体强度变化存在一定的影响.饱和黏土中静压桩的承载力具有时效性,静压桩周土体强度时变规律的解答能够为静压桩时变承载力的计算提供理论依据,具有重要的现实与科学意义.
[Abstract]:In the process of piling, the static pressure pile in natural saturated clay compacts the soil mass greatly, which results in the higher pore water pressure of the soil around the pile. After the piling is finished, the pile is gradually consolidated with the soil around the pile. In order to study the change law of soil strength around the pile after static pressure pile driving in saturated clay. Based on K0-MCC model and considering the influence of initial anisotropy and induced anisotropy on soil strength around pile, the solution of soil stress and superpore pressure after undrained expansion of column hole is derived. Based on the axisymmetric consolidation theory, the theoretical solution for the dissipation of the pore pressure around the pile is derived. On this basis, the relaxation effect of the soil around the pile in the consolidation process is considered. The time-varying effect of the soil strength around the pile after the pile sinking is analyzed, and the rationality of the solution is verified by centrifuge model test. This solution can reasonably predict the variation law of soil strength and super-pore pressure around the pile after the end of pile-driving, and the overconsolidation ratio of soil. The static lateral pressure coefficient and the effective internal friction angle of soil have some influence on the soil strength change around the pile, and the bearing capacity of the static pressure pile in saturated clay is time-dependent. The solution of time-varying law of soil strength around static pile can provide theoretical basis for calculation of time-varying bearing capacity of static pressure pile, which has important practical and scientific significance.
【作者单位】：岩土及地下工程教育部重点实验室(同济大学);同济大学地下建筑与工程系;
【基金】：国家自然科学基金(41272288)
【分类号】：TU473.1
【正文快照】： 静压桩由于施工速度快、工期短、不受季节限制、单桩承载力高等优点,在软土地区基础工程建设中得到了广泛应用[1-6].然而,静压桩作为挤土桩,其在压入饱和粘性土地基的过程中桩身将置换相同体积的土,对桩周土体产生巨大的挤压作用,使桩周土体中产生较高的超孔隙水压力,造成桩周

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