【作者】 马晔；

【导师】 张开银；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2008， 博士

【摘要】 随着交通事业的快速发展,超长钻孔灌注桩在跨越江河、海湾的大型桥梁建设中已经成为不可或缺的桥梁基础形式。但是,超长钻孔灌注桩承载性能的理论研究却落后于工程实践,还没有形成一套指导超长钻孔灌注桩设计的成熟理论;现有规范的计算方法和参数取值,并不能完全保证超长钻孔灌注桩的经济性和安全性。本论文针对超长钻孔灌注桩设计目前存在的某些问题,开展有针对性的研究工作。通过国内外资料收集和实地调研,全面掌握了目前超长钻孔灌注桩科研和应用情况,在此基础之上,进行荷载传递机理、现场测试技术、室内外试验,承载能力计算分析等多方面的研究工作,创新性研究成果有:(1)在对现场桩基试验及室内模型试验的桩土位移一应力进行曲线拟合统计与研究的基础上,提出了适合桩土位移的双曲线传递函数模型,建立了评价超长钻孔灌注桩承载力及位移的新方法。(2)在大量的现场试桩资料统计与分析的基础上,通过桩土刚度与桩长的关系分析和超长钻孔灌注桩的受力特征分析,首次阐明了超长钻孔灌注桩的定义及超长桩的定量界定,给出了超长钻孔桩桩侧摩阻力标准值的建议值和取值方法,为优化超长桩的设计提供了理论依据及今后修订公路桥梁桩基础设计规范提供了技术支撑。(3)首次提出桩土总刚度、桩土剪切刚度、桩端土抗压刚度等参数,建立超长钻孔灌注桩单桩承载力刚度协调计算法,使超长钻孔灌注桩的设计、计算更符合实际情况。(4)研发了具有自主知识产权的“大吨位基桩抗压静载试验中的预应力反力系统装置”(专利号为ZL2005 20114928.9),使锚桩法的试桩吨位得以提高,并能有效利用工程桩、承台和墩身,从而节约试桩的工程费用;(5)研发的“自锚桩法荷载箱”(专利号为ZL2005 20114929.3)可以消除荷载箱工作失真,提高测试精度,解决了自锚桩测桩法存在荷载～沉降曲线失真的技术难题。(6)把成孔检测技术在数十座公路桥梁桩基检测中进行推广,通过对大量工程桩基测试数据的统计分析,进一步掌握了钻孔灌注桩的扩孔率。本论文所取得的科研成果已在多个实体工程中推广和应用,其中大吨位桩基静荷载试验的应用工程有10个,成孔质量检测应用工程有14个,缺陷处理技术应用工程有4个,完成了13根锚桩一反力梁法试桩和7根自锚桩法试桩试验,以及2630根钻孔灌注桩成孔检测和13根桩的缺陷处治工作,取得了良好的社会和经济效益,其中锚桩反力梁法加载吨位最大达40000kN,为世界最大加载吨位。本项目科研成果的全面推广应用,将会大大节约公路大桥建设资金,提高桥梁基础建设的安全性,提升我国公路桥梁钻孔桩的试验、测试、设计及缺陷处治的总体水平。更多还原

【Abstract】 The super-long bored pile has become an indispensable style of foundation at the highway bridges,especially at the spanning great rivers and gulfs bridges.But researches of the engineering properties of super-long piles are not sufficient for the requests of application,and we have not a befitting theory to guide the designs and calculations of the super-long bored piles,at the same time the economy and security of the super-long bored piles are not ensured completely by the methods and parameters of the existing code.For the problems upwards,we have done much of pertinence work.By collecting data and investigating,we have comprehensively known the application and research status quo of super-long bored piles and we have done a great deal of researches including field test technology,load transfer mechanism,laboratory and field test,calculation and analysis of bearing capacity and so on,Our main innovative conclusions are as followings:●The displacement-stress curves of pile and soil gained from field load tests and indoor model tests have been simulated and analyzed,based on which the hyperbola function adapted to pile and soil are brought forward,and the new method is advanced to estimate the bearing capacity and displacement of the super-long bored piles.●On the basis of the statistic and analysis of vast data obtained form field load tests,for the first time we have elucidated the definition and the judgment method of super long pile by analyzing the relationship between the assembled stiffness and piles’ length and the super long piles’ property under load.Further more,the propositional standard values of pile shaft friction and its decision method are brought forward which will provide theoretical basis to optimize the design of super long piles,and will also support the technique basis to modify the Specifications for Design of Ground Base and Foundation of Highway Bridges and Culverts.●For the first time,we put forward the parameters such as the assembled stiffness,the shearing rigidity of pile and soil and compressive rigidity of pile-end soils and so on,and the harmonized stiffness method to calculate the bearing capacity of super-long bored pile has been put forward that would help the design and calculation of super-long bored pile according to the real instance much more.●We have invented the prestressed reaction force equipment used at large weight dead-load pile experiment with intellectual property(The patent code is ZL2005 2 0114928.9).This equipment can enhance the load weight greatly and reduce the expenditure by using the engineering piles caps and piers.●The load cell used in pile self-balanced load test(or O-cell pile testing method) we have designed(The patent code is ZL2005 2 0114929.3) can eliminate the distorted digital,elevate the testing precision,and this technique has solved the problem that the load- sedimentation curves don’t accord with the practice,so that the precision of O-cell pile testing method has been enhanced greatly.●The technology of using ultrasonic to inspect holes quality has been used at tens of great bridges.We have analyzed many data obtained from the inspection.The more accurate expanded ratio of design dia.of the super-long bored piles has been gained.Our research achievements have been popularized and applied at many bridge constructing projects,in ten of which,static load testing for piles with large bearing capacity have been used,in fourteen of which,the ultrasonic quality testing of bored holes have been used,in four of which pile disfigurement handling technique have been used.In total,13 anchor-pile loading tests,8 O-cell pile tests,2630 ultrasonic quality tests of bored holes and disfigurement handling for 13 piles have been finished and the results show that good societal and economic benefit has been gained. The maximal load has reached 40000kN in our static load test wit anchor pile and counterforce beam,which is the maximum load in the world with this method.The generalization and application all-around of our achievements will save the expense of highway bridges construction,enhance the security of bridges and boost the level of pile test inspection design and disfigurement handling.更多还原