摘要
为确定砂岩地层扩底桩抗拔承载特性,依托国网路平—富乐500 kV双回线路工程,对嵌岩抗拔桩进行现场静载试验,得到该嵌岩扩底桩的侧阻与轴力作用特征,进而提出嵌岩扩底桩极限承载力的简化计算法。分析表明:嵌岩扩底桩的上拔荷载-桩顶位移曲线为陡变型,增加桩长可以有效提高极限抗拔承载力;但底端扩大头的作用随着桩长的增加有所减弱,端身荷载承担比由69.9%逐步降至31.4%;短桩底端扩大头从加载初期即承担上拔荷载作用,而嵌岩长桩的扩大头则不一定,对于其应慎重采用底端扩大头;当桩身强度高于桩周岩体时,试桩等截面段的抗拔承载力由桩周岩体的抗剪切强度提供,其极限侧摩阻力可以等效为桩周岩体的抗剪切强度。
In order to study the uplift bearing characteristics of the rock-socketed belled pile in sandstone strata,based on the 500 kV double-circuit line project of State Grid,load tests for aixal uplift piles in situ for rock-socketed belled piles were conducted,and the characteristics of the side friction resistance and axial force of piles were obtained,and then a simplified calculation method for the ultimate bearing capacity of rock-socketed belled pile was proposed.The results of field tests showed that the curves of uplift loads and displacement for rock-socketed belled piles were steep,to increase the pile length could effectively improve the ultimate uplift bearing capacity of uplift piles,but with the increase of the pile length,the effect of belled end would decrease and the load bearing ratios of the pile tips and pile shafts gradually decreased from 69.9%to 31.4%;the belled ends of short belled piles bore the uplift loads at initial stages of being loaded,while the belled ends of long rock-socketed piles did not bear loads necessarily,so the belled ends for longer uplift piles were not necessary;when the strength of pile shafts was higher than that of rock around piles,the uplift bearing capacity of test piles was provided by the shear strength of rock around piles,and the ultimate side friction resistance could be equivalent to the shear strength of rock around piles.
作者
杨柏
肖世国
马建林
刘宝臣
苏春晖
YANG Bai;XIAO Shiguo;MA Jianlin;LIU Baochen;SU Chunhui(Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 610031,China;School of Architecture and Transportation Engineering,Guilin University of Electronic Technology,Guilin 541004,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《工业建筑》
CSCD
北大核心
2021年第4期132-138,147,共8页
Industrial Construction
基金
国家重点研发计划项目(2016YFC0802203)。
关键词
扩底桩
承载特性
现场试验
极限承载力
砂岩地层
belled piles
load-bearing characteristics
field test
ultimate bearing capacity
sandstone strata
