摘要
为研究地下车库基桩低应变检测的基本原理与检测方法,采用PDS-PS基桩动测仪、手锤和力棒等设备进行检测,获得反射波波速、完整性类别及反射波波形图等,研究结果表明:低应变反射波法简单易行、操作方便、快速灵活、效率高、耗费少,锤击能量小,属于无损检测;将基桩假定为一维均质弹性杆件模型即L桩长≥D桩径,通过锤击桩顶产生的应力波沿桩身向下传播,遇到桩身缺陷时,会产生反射和投射,通过完整性分析和打印的波形对桩身完整性做出判断;当桩身无缺陷时,Z1=Z2,VR=0,桩身内部不存在反射波,只存在桩底反射波;当桩身存在缺陷时,Z1> Z2,VR与VI同号,即在实测时域曲线上,反射波与入射波同相;当桩身存在扩径等原因而使波阻抗增大时,即Z1<Z2,VR与VI反号,即不在实测实域曲线上,反射波与入射波反相。当桩身存在缺陷时,根据接收到的缺陷反射波与锤击桩顶出发的时间差和声波在基桩内传播速度V来计算基桩内的缺陷位置;在140根基桩中抽取24根基桩进行完整性检测,Ⅰ类桩共有18根,占所测桩数比例为75%;Ⅱ类桩共6根,占所测桩数比例为25%;Ⅲ,Ⅳ类桩共0根;在140根基桩中抽取24根基桩进行检测,其中完整桩共有18根,占所测桩数比例为75%;缩桩共6根,占所测桩数比例为25;扩径桩、离析桩及断桩共0根;从基桩完整性类别和典型桩类别所占比例来看,所检测基桩完整性较好,桩身结构承载力较好,振动反应曲线较为规则,波形清晰、完整、直观。
In order to study the basic principle and detection method of the low-strain detection of the underground garage pile,the PDS-PS pile measuring instrument,hand hammer and force bar were used for testing to obtain the wave velocity,completeness of the reflected wave,and the waveform of the reflected wave. The research results show that: The low-strain reflected wave method is simple,easy to operate,quick and flexible,high in efficiency,low in cost,low in hammering energy,and is non-destructive testing. The pile is assumed to be one-dimensionally homogeneous. The elastic rod model is the L≥D. The stress wave generated by hammering the pile top propagates down the pile body. When the pile body defect is encountered,it will produce reflection and projection,through the integrity analysis and the printed waveform. Determine the integrity of the pile body. When there is no defect in the pile body,Z1= Z2,VR= 0,there is no reflection wave inside the pile body,there is only reflected wave at the bottom of the pile;When there is defect in the pile body,Z1> Z2,VRand VIhave the same number,that is,in the measured time domain curve,the reflected wave is in phase with the incident wave;when the pile body has reasons such as expanding the diameter,so that the impedance of the wave increases,ie,Z1< Z2,the opposite sign of VRand VIThis means that the reflected wave is in antiphase with the incident wave. When there is a defect in the pile,the position of the defect in the pile is calculated based on the time difference Δt between the reflected wave of the defect and the starting point of the hammered pile and the propagation velocity V of the acoustic wave in the pile. Extraction from 140 piles 24 foundation piles were tested for integrity. There were 18 I-type piles,accounting for 75% of the measured piles. 6 II-type piles,which accounted for 25% of the measured piles,and 0,III and IV piles.In the 140 foundation piles,24 foundation piles were selected for testing,among which 18 were intact piles,which accounted for 75% of the
作者
谢财进
饶军应
梁中勇
刘宁
赵霞
刘灯凯
XIE Caijin;RAO Junying;LIANG Zhongyong;LIU Ning;ZHAO Xia;LIU Dengkai(College of Civil Engineering,Guizhou University,Guiyang,Guizhou 550025,China)
出处
《施工技术》
CAS
2018年第A02期27-31,共5页
Construction Technology
基金
国家自然科学基金资助项目(51608141)
贵州省科技计划项目(黔科合基础[2016]1041)
贵州省土木工程一流学科建设项目(QYNYL[2017]0013)
关键词
基桩低应变检测
反射波波速
反射波波形
完整性类别
典型桩类别
基桩完整性
振动反应曲线
low strain detection of pile foundation
wave velocity of reflected wave
waveform of reflected wave
integrity category
typical pile type
pile integrity
vibration response curve
