摘要
为分析褥垫层中加筋体对PCC桩复合地基承载特性的影响,以自行开发的大型桩基试验系统为依托,开展PCC桩复合地基室内足尺模型试验,详细介绍足尺试验准备与开展,重点进行9种加筋褥垫层的对比试验研究。试验表明:加筋褥垫层能保证PCC桩与桩间土共同承担荷载,加筋体设置方式会对复合地基的承载特性产生影响。在相同的荷载下,随着加筋材料层数的增加,从无筋到单层加筋再到双层加筋,加筋垫层对桩顶刺入垫层限制作用增强,加载板沉降量是减小的,但桩土应力比、桩身各处轴力、桩芯土压力和内摩阻力都是增大的。此外,通过桩顶直接传递给桩体的荷载比例是逐渐增加的,而由负摩阻力传递给桩体的荷载却是在减小,通过这2条途径所传递给桩体的总荷载比例是增大的,桩体同样起到了传递荷载的主要作用。
Cushion is one of the key parts of composite foundation with the thin-wall pipe piles made of cast-in-situ concrete（PCC） and makes the piles and soil to work together. The cushion is usually made of gravel with geogrid reinforcement in practice. The characteristics of cushion,such as the thickness,the reinforcement layers and types,affect the load sharing of piles and soil,which affect the load transfer mechanism of the composite foundation. A large model testing system of simulating the full scale pile foundations was developed and described in this paper. The load transfer mechanism of PCC pile composite foundation was studied with the full scale model tests. The effects of nine different types of cushions on the load transfer mechanism were studied, including the load-settlement curve,the pile-soil stress ratio,the axial force in piles,and the soil pressure and friction inside the pile wall. The testing results show that with the increase of the number of geogrid reinforcement layers,the pile-soil stress ratio,the pile axial force,and the soil pressure and friction inside the piles were all increased;and the settlement was decreased under the same amount of load. Piles always played a major role in load carrying in the composite foundation. The loads transferred to the pile heads were increased and the negative friction force onto the piles was decreased.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2014年第12期2531-2538,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51309087)
中央高校基本科研业务费专项资金资助项目(2013B31414)
关键词
基础工程
复合地基
加筋褥垫层
PCC桩
模型试验
承载特性
foundation engineering
composite foundation
geogrid-reinforced cushion
PCC pile
model test
bearing behavior
