摘要
阶梯型变截面桩竖向承载力大,但其在变径处应力集中现象明显,限制了该桩型的适用范围,为减轻其在变径处的轴力突变,将水平变截面设置为一定倾角,形成锥型组合桩。为了摸清该新桩型的竖向承载性能,基于室内模型试验对锥型组合桩在竖向荷载作用下的力学响应进行测试,并与传统等截面桩、阶梯型桩进行对比,揭示锥型组合桩的竖向承载机理。模型试验依据相似理论进行设计,在试验中保持三种桩型的体积近似相等,竖向荷载采用分级加载,获取桩顶沉降曲线以及桩身轴力分布。研究结果表明:(1)等截面桩的竖向承载力最小,阶梯型桩的竖向承载力居中,锥型组合桩的竖向承载力最大;(2)等截面桩的轴力随深度增大近似线性减小,阶梯型桩在截面变小处轴力发生突变,产生应力集中,锥型组合桩在上下两个截面变化处轴力未发生显著突变,在下变截面处往下一定位置产生轴力极大值,轴力分布较为均衡;(3)等截面桩侧阻力占比随荷载增大急剧减小,阶梯型桩侧阻力占比随着荷载非线性变化,锥型组合桩侧阻力占比稳定在55%左右;(4)锥型组合桩既可以发挥阶梯型桩承载力大的优点,又可以克服阶梯型桩在变截面处的轴力突变问题,竖向承载力大于阶梯型桩,具有良好的工程应用价值。
The step-tapered pile has a large vertical bearing capacity,but the stress concentration phenomenon is obvious at the variable cross-section,which limits the application range of this pile type.In order to reduce the abrupt change of axial force at the variable cross-section,the taper angle was employed in the design of the step-tapered pile to form the conical composite pile. To determine the vertical bearing capacity of the new type of pile,the static response of the conical composite pile under vertical load was tested based on the physical scale model test,and the behaviors of the conical composite pile were revealed by comparing it with the traditional uniform-section pile and step-tapered pile. The model test was designed according to the similarity theory and the volume of the three types of the pile was approximately equal. The vertical load was applied on the pile head by steps,then the settlement curve and the axial force of the pile under loading were obtained. The results show that :(1)The vertical bearing capacity of the uniform-section pile was the smallest,that of the step-tapered pile was in the middle,and that of the conical composite pile was the largest.(2)The axial force of the uniform-section pile decreased approximately linearly with the increase of depth. The axial force of the step-tapered pile changed sharply when the cross-section became smaller,while that of the conetype pile did not change remarkably at the upper and lower variable sections. The position of the maximum axial force of conical composite was located below the lower variable section,and the overall axial force distribution was more harmonious.(3)The ratio of shaft resistance of uniform-section piles decreased sharply with the increase of load,while that of step-tapered piles changed non-linearly with the increase of load. The ratio of shaft resistance of conical composite piles was stable at around 55%.(4)The conical composite pile can not only give full play to the advantages of the large bearing capacity of the step-tape
作者
周先齐
叶金铋
金晓勤
郭登圻
ZHOU Xianqi;YE Jinbi;JIN Xiaoqin;GUO Dengqi(College of Civil Engineering and Architecture,Xiamen University of Technology,Xiamen 361024,China;Fujian Provincial Key Laboratory of Wind Disaster and Wind Engineering,Xiamen University of Techonolgy,Xiamen 361024,China)
出处
《防灾减灾工程学报》
CSCD
北大核心
2022年第5期1097-1103,共7页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(42077254,51874144)
福建省自然科学基金(2020J05238,2020J01280)资助。
关键词
锥型组合桩
模型试验
倾角
竖向承载力
conical composite pile
model test
angle
vertical bearing capacity
