砂土地基中静压桩沉桩及其承载特性室内试验研究  

Experimental investigation on resistance and response of jacked model piles in sand

作　　者：肖昭然[1] 王艳林 赵宪强 蒋敏敏[1] 赵文才 XIAO Zhaoran;WANG Yanlin;ZHAO Xianqiang;JIANG Minmin;ZHAO Wencai(College of Civil Engineering,Henan University of Technology,Zhengzhou 450001,China;Geotechnical Engineering Department,Nanjing Hydraulic Research Institute,Nanjing 210024,China;College of Civil and Transportation Engineering,Hohai University,Nanjing 210024,China;Henan Jianke Foundation Engineering Co.,Limited,Zhengzhou 450000,China)

机构地区：[1]河南工业大学土木工程学院,河南郑州450001 [2]南京水利科学研究院岩土工程研究所,江苏南京210024 [3]河海大学土木与交通学院,江苏南京210024 [4]河南省建科基础工程有限公司,河南郑州450000

出　　处：《建筑结构学报》2022年第11期294-302,共9页Journal of Building Structures

基　　金：国家自然科学基金项目(50978086,51178165)。

摘　　要：静压沉桩过程中沉桩阻力计算是桩机选型的关键,而目前对沉桩阻力计算方法尚未统一,且沉桩过程中引起的桩周侧压应力分布规律尚不明确。为此,通过室内模型试验模拟砂土地基中静压沉桩,研究沉桩速率和桩长对静压沉桩过程中沉桩阻力、沉桩端阻力、桩周侧压应力和桩体极限承载力的影响。结果表明:沉桩阻力、沉桩端阻力、桩周侧压应力和桩体极限承载力主要与桩长有关,沉桩端阻力与沉桩阻力之比随着沉桩深度增加而减小,但在沉桩深度为12倍桩径位置的沉桩端阻力占沉桩阻力的比例仍高达75%;桩周侧压应力随着埋深增加逐渐趋近于被动土压力,其主要与沉桩对土体挤密作用有关,且增加桩长和降低沉桩速率均可改善沉桩挤密作用;桩周侧压应力存在显著的“退化”现象,并与沉桩过程和桩体回弹有关。此外,基于太沙基极限承载力理论建立了沉桩阻力拟合计算式,并结合朗肯被动土压力理论,提出了桩周侧压应力计算的朗肯被动土压力修正计算公式,可用于静压桩沉桩完成后的桩周侧压应力计算。The installation resistance is important for selecting the type of jacked equipment.However,the calculation method of installation resistance has not been unified,and the radial stress distribution law of the soil surrounding the pile caused by installation pile is not yet clear.In this paper,a series of tests were performed on model pile jacked in sand,and the driven speed and pile length were considered.The changes of installation resistance,end resistance,radial stress and ultimate capacity of pile of jacked pile were analyzed.The pile length is the most significant factor that affects installation resistance,end resistance,radial stress and ultimate capacity of piles.Although the ratio of end resistance to installation resistance decreases with the depth,the end resistance is always dominant in the installation process of piles,and the ratio of end resistance to installation resistance is up to 75%when the depth is 12 times of pile diameter.The tendency for the radial stress of the soil surrounding the pile is closer to Rankine’s earth pressure with the depth.It is related to the compaction effect of jacked pile,increasing pile length or reducing the driving speed can improve the compaction effect of jacked pile.The radial stress of the soil surrounding the pile has a degradation phenomenon,which is related to the jacking pile and the pile rebound.Moreover,a modified methodology was proposed based on Terzaghi’s bearing capacity theory.Combined with the theory of Rankin passive earth pressure,the calculation formula of Rankin passive earth pessure correction for the radial stress of the soil surrounding the pile calculation was proposed,which can be used for the radial stress of the soil surrounding the pile after the installation pile.

关 键 词：桩基础 砂土地基 静压桩 模型试验 沉桩阻力 桩周侧压应力 

分 类 号：TU473.12[建筑科学—结构工程]