Determination of ultimate bearing capacity of uplift piles using intact and non-intact load−displacement curve  

利用完整和非完整荷载−位移曲线确定抗拔桩的极限承载力

作　　者：WANG Qin-ke MAJian-lin JI Yu-kun ZHANG Jian CHEN Wen-long 王钦科;马建林;季雨坤;张健;陈文龙(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;School of Chemistry,University of Nottingham,Nottingham NG72RD,United Kingdom;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China [2]School of Chemistry,University of Nottingham,Nottingham NG72RD,United Kingdom [3]State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China

出　　处：《Journal of Central South University》2022年第2期470-485,共16页中南大学学报（英文版）

基　　金：Project(2016YFC0802203)supported by the National Key R&D Program of China;Project(2013G001-A-2)supported by the Science and Technology Research and Development Program of China Railway Corporation;Project(SKLGDUEK2011)supported by the State Key Laboratory for GeoMechanics and Deep Underground Engineering,China University of Mining&Technology。

摘　　要：Based on the field destructive test of six rock-socketed piles with shallow overburden,three prediction models are used to quantitatively analyze and predict the intact load−displacement curve.The predicted values of ultimate uplift capacity were further determined by four methods(displacement controlling method(DCM),reduction coefficient method(RCM),maximum curvature method(MCM),and critical stiffness method(CSM))and compared with the measured value.Through the analysis of the relationship between the change rate of pullout stiffness and displacement,a method used to determine the ultimate uplift capacity via non-intact load−displacement curve was proposed.The results show that the predicted value determined by DCM is more conservative,while the predicted value determined by MCM is larger than the measured value.This suggests that RCM and CSM in engineering applications can be preferentially applied.Moreover,the development law of the change rate of pullout stiffness with displacement agrees well with the attenuation form of power function.The theoretical predicted results of ultimate uplift capacity based on the change rate of pullout stiffness will not be affected by the integrity of the curve.The method is simple and applicable for the piles that are not loaded to failure state,and thus provides new insights into ultimate uplift capacity determination of test piles.基于6根浅覆盖层嵌岩桩的现场破坏性试验,采用3种预测模型对完整的荷载−位移曲线进行定量分析和预测。通过位移控制法(DCM),折减系数法(RCM),最大曲率法(MCM),临界刚度法(CSM)4种方法进一步确定了极限抗拔承载力的预测值,并与实测值进行了比较。通过分析抗拔刚度变化率与位移之间的关系,提出了一种利用非完整荷载−位移曲线确定极限抗拔承载力的方法。结果表明,通过DCM确定的预测值较为保守,而MCM确定的预测值大于实测值,建议在工程应用中优先采用RCM和CSM。抗拔刚度变化率随位移的变化规律与幂函数的衰减形式吻合较好。基于抗拔刚度变化率的极限抗拔承载力理论预测结果不受曲线完整度的影响。该方法简单易行,适用于未加载到破坏状态的桩,为试桩极限抗拔承载力的确定提供了新的思路。

关 键 词：load−displacement curve prediction model determination method of bearing capacity change rate of pullout stiffness 

分 类 号：TU473.11[建筑科学—结构工程]