南宁市下伏泥岩粉砂岩地基具有显著的浸水崩解软化特性,使得该地基大直径灌注桩承载力难以确定。依托南宁市火车东站南广场高架平台工程软岩互层地基大直径灌注桩项目,对该工程2根群桩基桩进行了静载试验研究。针对试验中试桩未达到破坏其极限承载力难以确定问题,采用指数函数拟合法和数值反演分析法来预测其荷载沉降性状和极限承载力,并进行对比分析。结果表明:软岩互层地基桩基荷载沉降性状为缓变型,表现出端承摩擦桩的特性,可用指数函数来描述试桩受荷性状,并结合数值反演分析来预测其极限承载力,目前常用的桩基设计方法低估了该地基中基桩的承载力。
Abstract
The bearing capacity of cast-in-place bored pile of large diameter in soft rock foundation in Nanning is difficult to determine due to softening and disintegration characteristics when soaked in water. Static load test was conducted to determine the bearing capacity of bored pile in the soft rock interbedding foundation of an elevated platform project in the railway station of Nanning Ciy. Both exponential function fitting method and numerical back analysis were used to accurately predict the load-settlement relation and ultimate bearing capacity of test pile which did not reach the ultimate state. Results show that the load-settlement curve of bored pile in soft rock interbedding foundation is an adjustment curve and the pile works as end bearing friction pile. As common design methods of pile foundation at present underestimates the bearing capacity of pile in this foundation, exponential function which is used to describe the load-settlement behaviour of test pile and numerical back analysis can be combined to estimate the ultimate bearing capacity of test pile.
关键词
灌注桩 /
静载试验 /
极限承载力预测 /
指数模型 /
数值反演分析
Key words
bored pile /
static load test /
prediction of ultimate bearing capacity /
exponential model /
numerical back analysis
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 程 晔,龚维明,戴国亮,等. 软岩桩基承载性能试验研究[J]. 岩石力学与工程学报,2009,28(1): 165-172.[2]RANDOLPH M F. Science and Empiricism in Pile Foundation Design[J]. Geótechnique,2003, 53(10): 847-875.[3] COMODROMOS E M, PAPADOPOULOU M C, RENTZEPERIS I K. Pile Foundation Analysis and Design Using Experimental Data and 3-D Numerical Analysis[J]. Computers and Geotechnics,2009,36(5):819-836.[4]JGJ 106—2014,建筑基桩检测技术规范[S]. 北京:中国建筑工业出版社, 2014.[5] 赵明华. 桥梁桩基计算与检测[M].北京:人民交通出版社, 2000.[6] 何 健. 解析法推算桩极限荷载和划分桩类别的探讨[J]. 建筑结构,1993,(2): 26-31.[7] 修朝英,李大展. 单桩垂直静载试验P-S曲线的数学描述和极限荷载的预测[J]. 岩土工程学报,1988,10(6): 64-73.[8] 赵春风,李尚飞,鲁 嘉,等. 完整指数函数拟合单桩荷载-沉降曲线的分析[J]. 同济大学学报(自然科学版),2010,38(4): 486-492.[9] 赵春风,于明章. 试桩未达破坏时单桩极限承载力的估算方法[J]. 同济大学学报(自然科学版),1999, 27(4): 474-477.[10]徐新跃. 桩基极限承载力预测方法的研究[C]∥中国岩石力学与工程学会第七次学术论坛大会论文集. 西安:中国科学技术出版社, 2002:786-791.[11]邓志勇,陆培毅. 几种单桩竖向极限承载力预测模型的对比分析[J]. 岩土力学,2002,23(4): 428-464.[12]欧阳明,丁伯阳,石吉森. 单桩荷载-沉降曲线的修正指数曲线模型拟合研究[J]. 水运工程, 2013,(1): 31-38.[13]马 艳,张 昊,王俊林. 大直径超长混凝土灌注桩极限承载力预测[J]. 信阳师范学院学报:自然科学版,2012, 25(1): 127-129.[14]COMODROMOS E M,ANAGNOSTOPOULOS C T,GEORGIADIS M K. Numerical Assessment of Axial Pile Group Response Based on Load Test[J]. Computers and Geotechnics,2003, 30(6): 505-515.[15]杜家庆,杜守继,赵丹蕾,等. 竖向荷载下群桩-土-承台相互作用数值分析[J]. 岩土力学,2013,34(8): 2414-2420.[16]COMODROMOS E M, BAREKA S V. Evaluation of Negative Skin Friction Effects in Pile Foundations Using 3D Nonlinear Analysis[J]. Computers and Geotechnics,2005, 32(3): 210-221.[17]POTYONDY J G. Skin Friction between Various Soils and Construction Materials[J]. Geótechnique,1961,11(4): 339-353.[18]ACER Y B, DURGUNOGLU H T, TUMAY M T. Interface Properties of Sands[J]. Journal of Geotechnical Engineering,1982, 108(4): 648-654.[19]陈育民,徐鼎平. FLAC/FLAC3D基础与工程实例[M]. 2版. 北京: 中国水利水电出版社, 2013.[20]洪 鑫. 单桩静载荷试验的理论模拟及影响因素分析[J]. 岩土工程学报,2012,34(1): 176-183.
基金
国家自然科学基金项目(51568006,41362016); 中国博士后科学基金项目(2017M612865); 广西重点实验室系统性研究项目(2016ZDX11);广西岩土力学与工程重点实验室资助课题(14-KF-03,13-KF-02); 广西博士后专项资助项目
PDF(2435 KB)
