超大厚度Q_2黄土场地单桩承载力试验研究  

EXPERIMENTAL STUDY OF BEARING CAPACITY OF SINGLE PILE IN LARGE THICKNESS Q_2 LOESS GROUND

作　　者：朱彦鹏[1,2] 董芸秀 包泽学 马天忠[1,2] 来春景[1,2] 

机构地区：[1]兰州理工大学甘肃省土木工程防灾减灾重点实验室,甘肃兰州730050 [2]兰州理工大学西部土木工程防灾减灾教育部工程研究中心,甘肃兰州730050

出　　处：《岩石力学与工程学报》2014年第A02期4375-4383,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：教育部长江学者创新团队计划(IRT1368);甘肃省创新研究群体资助项目(1210RJIA003)

摘　　要：目前对于湿陷性较弱或无湿陷性的Q2离石黄土层上桩基性能的研究非常匮乏。为确定超大厚度黄土地区Q2离石黄土层上的桩基承载力,进行现场单桩静载荷试验。在试桩桩身布置混凝土应变计和钢筋应力计,桩端布置土压力盒,对试桩进行现场内力测试。研究结果表明:(1)桩身轴力和桩侧摩阻力两者随桩身范围内的分布规律不仅与桩顶荷载的大小有关,而且与桩周土的性质有关。(2)当桩顶荷载Pt与桩顶加载极限值Pu之比小于0.80(Pt/Pu<0.80)时,桩顶沉降主要是由桩身弹性压缩引起的;当Pt/Pu≥0.80时,在计算桩身沉降量时应考虑桩端土体的沉降量Sb。(3)规范简化法中对综合系数的取值偏大,建议取=0.44作为本地区同类型桩的计算参数。从简化法和线性法出发,提出一种利用桩身压缩量来预估单桩沉降的新方法。Research on the performance of pile for the weak or non-collapsible Q2 Lishi loess layer is very scarce. In order to determine the pile Q2 Lishi loess layer thickness on the large pile in loess area,the single pile static load test was carried out. Concrete strain gauges and reinforcement stress meter are arranged on test piles,and soil pressure cells were installed on pile bottom to test internal forces on-site. Results show that：（1） Distribution of axial force of pile and lateral friction along the pile is not only related to pile top load,but also related to the nature of pile side soil.（2） When the ratio of pile top load and limit value of pile top load is less than 0.80（Pt/Pu0.80）,pile top settlement is mainly caused by the elastic compression of pile;when Pt/Pu≥0.80,endpoint soil subsidence Sb should be considered when calculating the pile settlement.（3） Standardized coefficient of the simplified method of synthetic factor value slants big,it is recommended to take ζ = 0.44 in the region of the same type as the pile of calculation parameters. A new way was put forward by using amount of pile body compression to estimate the settlement of single pile in terms of simplified method and linear method.

关 键 词：桩基础 单桩静荷载试验 单桩承载力 桩身轴力 桩侧摩阻力 桩身压缩变形 

分 类 号：TU473[建筑科学—结构工程]