软土次固结阶段桩侧负摩阻力变化规律研究  

THE VARIATION LAW OF NEGATIVE SKIN FRICTION OF PILE DURING SECONDARY-CONSOLIDATION OF SOFT SOIL

作　　者：张建新[1,2] 岳晓鹏[1] 刘举[1,2] 蒋坪临 

机构地区：[1]天津城建大学土木工程学院,天津300384 [2]天津市软土特性与工程环境重点实验室,天津300384

出　　处：《工程地质学报》2017年第3期692-698,共7页Journal of Engineering Geology

基　　金：天津市自然基金重点项目(13JCZDJC35500);天津市软土特性与工程环境重点实验室开放基金(2012SCEEKL003)资助

摘　　要：设计软黏土中单桩模型箱试验,模拟了桩周土逐级加荷沉降,通过量测超孔隙水压力、土体沉降及桩身轴力变化,分析了软黏土进入次固结阶段时,桩侧负摩阻力及桩身中性点位置变化情况。研究表明,在次固结阶段桩周土所产生的沉降对桩侧负摩阻力仍具有一定影响,沿桩身呈先增大后减小的趋势;当桩周土所施荷载等级达到一定程度时,桩身中性点位置将随着桩周土次固结时间的增长而逐渐上移。次固结阶段产生的沉降量与土体上所施加的荷载等级有关,随着桩周土荷载等级的增大,次固结阶段产生的沉降所占总沉降的比例逐渐减小,其蠕变效应逐渐减弱。This paper designs single pile model box test in soft clay to simulate the pile settlement of progressive loading. It measures the change of the excess pore water pressure, surface settlement and pile axial force measurement. The influence of the lateral mode resistance of the pile foundation and the change of the position of the neutral point are analyzed when the soft clay is in the stage of secondary consolidation. The research shows that the settlement caused by the soil in the secondary consolidation stage has a certain effect on the negative skin frictional resistance. Along the pile,the negative skin frictional resistance is first increased and then decreased.When the load level is up to a certain degree,the neutral point can move up as the consolidation time of the soil around the pile increases,the settlement caused during the secondary consolidation stage is related to the load level applied to the soil around the pile. As the load level of the pile increases,the proportion of the total settlement of the secondary-consolidation stage decreases gradually. The creep effect of the pile is gradually weakened.

关 键 词：次固结 桩侧负摩阻力 超孔隙水压力 中性点 土体沉降 

分 类 号：TU443[建筑科学—岩土工程]