摘要
阐述了堆载法静载试验中桩侧堆载与地基变形对试桩的影响,为便于分析,定义了试桩沉降的实测值和真实值。对比分析了国家、行业及地方标准中关于试桩、锚桩(或压重平台支墩)和基准桩之间中心距离的相关规定,探讨了减小桩侧堆载对试桩沉降影响的方法。结合深圳填海区大直径超长桩静载试验工程实例,建立三维数值模型,分析了采用地基处理+"回"字形混凝土平台时,桩侧堆载和加/卸载方式对试桩受荷性状及测试结果的影响,包括桩土沉降、桩身轴力、监测点位移和试桩刚度等。研究结果表明:堆载法静载试验中,采用试桩沉降真实值时,桩侧堆载的加/卸载过程对试桩极限承载力和承载特性的影响可以忽略;对于采用"回"字形混凝土平台的软土地基大直径超长桩静载试验,建议采用高精度水准仪或全站仪对试桩桩顶沉降真实值进行监测和校核,包括试验准备阶段桩侧堆载引起的沉降,以剔除桩侧堆载的加/卸载过程对沉降基准点竖向位移的影响。
The effects of surrounding load and ground deformation on the test pile were analyzed for the static load test.The measured value and actual value of the test pile settlement were defined.Relevant rules in the national,professional and regional standards about the center distances between the test pile,anchor pile(or the buttress)and benchmark pile were discussed and the method to reduce the effect of surrounding load on the test pile settlement was investigated.Based on the actual case of static load test of large-diameter super-long pile located at the reclamation area in Shenzhen,a 3 D numerical model was built to analyze the effect of surrounding load and loading method on the bearing performance of test pile and the test results,including pile-soil settlement,axial force of pile,displacement of monitoring point and secant stiffness of test pile,of which ground improvement and platform with hollow square were adopted.The results show that if the actual settlement of the test pile is used,the effect of loading/unloading process of surrounding load on limit bearing capacity and bearing performance can be ignored.For static load test of large-diameter super-long pile using platform with hollow square in the soft soil foundation,leveling instrument with high precision or total station are recommended to monitor and check the actual settlement of the pile top,including the settlement induced by the surrounding load of the pile during the test preparation stage,in order to get rid of the adverse effect of loading/unloading of surrounding load on the vertical displacement of reference point.
作者
曹文昭
杨志银
蔡巧灵
高磊
CAO Wen-zhao;YANG Zhi-yin;CAI Qiao-ling;GAO Lei(Central Research Institute of Building and Construction(Shenzhen)Co.,Ltd.,Shenzhen 518055,Guangdong,China;Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210024,Jiangsu,China)
出处
《建筑科学与工程学报》
CAS
北大核心
2021年第6期1-10,共10页
Journal of Architecture and Civil Engineering
基金
中冶建筑研究总院有限公司重大项目(YJA2018Kj02)
国家自然科学基金项目(51808243)
河海大学岩土力学与堤坝工程教育部重点实验室开放基金项目(2019)。
关键词
软土地基
静载试验
数值模拟
桩侧堆载
加载方式
沉降
soft soil foundation
static load test
numerical simulation
surrounding load of pile
loading method
settlement
