深厚回填土中嵌岩灌注桩承载性状现场试验研究  

Study on field test of bearing capacity of punching rock-socket pile covered by deep backfill

作　　者：陈小钰 张明义[1,2] 白晓宇[1,2] 闫楠 桑松魁 CHEN Xiaoyu;ZHANG Mingyi;BAI Xiaoyu;YAN Nan;SANG Songkui(School of Civil Engineering,Qingdao University of Technology,Qingdao 266033,China;Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone,Qingdao University of Technology,Qingdao 266033,China;College of Environmental Science and Engineering,Qingdao University,Qingdao 266071,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266033 [2]青岛理工大学蓝色经济区工程建设与安全协同创新中心,山东青岛266033 [3]青岛大学环境科学与工程学院,山东青岛266071

出　　处：《中南大学学报（自然科学版）》2018年第7期1799-1807,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51708316;51778312);山东省重点研发计划项目(2017GSF16107;2018GSF117008);山东省自然科学基金资助项目(ZR2016EEQ08;ZR2017PEE006);山东省高等学校科技计划项目(J16LG02);青岛市应用基础研究计划项目(16-5-1-39-jch);中国博士后科学基金资助项目(2018M632641)~~

摘　　要：以青岛某重点工程为依托,对6根冲孔嵌岩灌注桩进行大吨位竖向静载荷试验与桩身内力测试(其中3根试桩加载至极限状态),探讨深厚回填土中(厚度为10 m)嵌岩灌注桩的荷载传递机理与竖向承载特性,分析强夯预处理技术对深厚回填土承载力的影响,总结现存嵌岩段极限侧摩阻力估算方法并评估其在本场地条件下的适用性。研究结果表明:6根试桩荷载-沉降曲线均为缓慢型,沉降与桩顶荷载呈非线性关系;桩顶沉降介于23~60 mm,且卸载回弹率较大,多数超过50%,嵌岩灌注桩的弹性工作性状较明显;在极限荷载状态下,桩端分担的桩顶荷载高达50%,嵌岩段侧摩阻力高达750 k Pa。强夯后回填土层的桩侧摩阻力由30 k Pa上升至120 k Pa,桩顶沉降平均值约为21 mm,约为未强夯处理回填土层中基桩沉降的50%;与采用Hoek-Brown破坏准则的理论估算法相比,基于岩石单轴抗压强度(UCS)的经验法较简单且能提供较为合理的估算值,且当折减系数取0.200~0.225时,误差率小于10%。Based on an important project in Qingdao,static compression tests were performed on six well-instrumented bored rock-socked testing piles,in which three piles were conducted to ultimate status.Transfer mechanism and vertical bearing capacity of testing piles installed in deep backfill were discussed,and effects of the dynamic compression pretreatment technology on the bearing capacity of the deep backfill were analyzed.Conventional methods of estimating rock rocket side resistance were summarized and their applicability on this site condition was assessed.The results show that load-displace curves of six testing piles are in slow type,and their displacement increases nonlinearly with applied loads.The head settlement is between 23?60 mm,with high unload resilience rate of more than 50%,indicating the resilience ability of testing piles.The rate of head load provided by base resistance is up to 50%at ultimate condition,and the average ultimate side resistance along shaft installed into rock is up to 750 kPa.The average lower head displacement of testing piles covered by after-treated backfill is 21 mm,which is half of the regular piles,and its resistance friction of backfill increases from 30 kPa to 120 kPa.Empirical correlation based on uniaxial compression strength(UCS)provides more reasonable and practical estimation than the theoretical assessment using Hoek?Brown criterion,and the error rate of estimation value is less than 10%when reduction coefficient ranges from 0.200 to 0.225.

关 键 词：冲孔嵌岩灌注桩 深厚回填土 轴力 极限侧摩阻力 

分 类 号：TU473.1[建筑科学—结构工程]