摘要
为了研究既有建筑物基桩低应变法的影响因素,采用低应变法对9根既有基桩进行完整性检测试验研究。以一维应力波理论为基础,探讨了既有基桩不同桩径条件下的完整性信号特征及不同承台尺寸下应力波的传播规律。结果表明:相同承台尺寸下,采用承台顶面击振且基桩-承台直径比为0.5时,测试曲线在桩头附近存在受承台影响的“缺陷”信号,易对既有基桩完整性造成误判。不同承台尺寸下,采用承台顶面击振时,随着承台高度和承台直径的增大,测试曲线在桩头附近存在“缺陷”信号,并且采用桩侧击振时,测试曲线中除了桩头附近“缺陷”信号更为明显外,桩底反射与承台二次反射波的叠加导致采集的曲线更加复杂,易造成既有基桩桩身完整性和桩长(或桩底反射)的误判。综上所述,在信号采集过程中,建议在按照优先级顺序先后采用承台顶面击振顶面接收,桩侧击振桩侧接收的方式,提高既有基桩低应变法检测信号质量和完整性判定的准确性。
In order to study the factors influencing the integrity of the low strain method of the existing building foundation pile, the low strain method was used to conduct experimental research on indoor model piles. Based on the one-dimensional stress wave theory, the integrity signal characteristics of existing foundation piles under different pile diameter conditions and the propagation law of stress waves under different pile sizes are discussed. The results show that under the same pile size, when the top surface of the pile is used to shock and the diameter ratio of the pile to the pile is 0.5, there is a “defect” signal affected by the pile near the pile head, which is easy to misjudge the integrity of the existing pile. Under different pile sizes, when the top surface of the pile is used to shock, with the increase of the height of the pile and the diameter of the pile, there is a “defect” signal near the pile head, and when the pile side vibration is used, in addition to the “defect” signal near the pile head in the test curve, the superposition of the pile bottom reflection and the secondary reflection wave of the pile platform leads to the acquisition curve being more complicated, which is easy to cause the misjudgment of the integrity of the pile body and the pile length(or pile bottom reflection) of the existing foundation pile. In summary, in the process of signal acquisition, it is recommended to use the top surface of the pile in the order of priority to receive the top surface of the pile, receive the top surface of the pile, and receive the pile side to improve the accuracy of the signal quality and integrity judgment of the existing pile low strain method.
作者
冯卓轩
胡贺松
刘春林
陈煜烽
徐明江
FENG Zhuoxuan;HU Hesong;LIU Chunlin;CHEN Yufeng;XU Mingjiang(Guangzhou Testing Centre of Construction Quality and Safety Co.,Ltd.,Guangzhou 510440,China;Guangzhou Construction Engineering Co.,Ltd.,Guangzhou 510030,China;School of Civil Engineering and Transportation,South China University of Technology,Guangzhou 510641,China)
出处
《建筑结构》
CSCD
北大核心
2022年第S02期2572-2576,共5页
Building Structure
基金
国家自然科学基金项目(51908225)
广州市建筑集团科技计划项目(2020-KJ007、2021-KJ007)
广州市建筑科学研究院科技进步项目(2021Y-KJ04、2022Y-KJ01)
关键词
低应变法
既有建筑物基桩
应力波
承台干扰
完整性判定
low strain method
existing foundation pile
stress waves
cap interference
completeness determination
