CAJ | 학술논문

通过低应变法检测基桩的现场试验，对比研究传感器安装位置对首波幅值及初至时间、桩底反射幅值及到达时间、检测波速等的影响特征。试验表明，由于首波时间滞后的影响，对于相同长度的桩，桩径越大，检测波速偏高越多；对于相同桩径的桩，长度越短，检测波速偏高越多。为提高低应变法检测的准确性，经理论分析，建立考虑时间滞后的针对灌注桩和预应力管桩的完整桩纵波速度计算公式、桩身缺陷位置计算公式，并首次提出灌注桩桩身下部缺陷段的平均波速计算公式。实践证明，提出的计算公式能正确反映桩身的实际纵波速度、桩身缺陷实际位置，较现有的计算公式有明显的优越性。
통과저응변법검측기장적현장시험，대비연구전감기안장위치대수파폭치급초지시간、장저반사폭치급도체시간、검측파속등적영향특정。시험표명，유우수파시간체후적영향，대우상동장도적장，장경월대，검측파속편고월다；대우상동장경적장，장도월단，검측파속편고월다。위제고저응변법검측적준학성，경이론분석，건립고필시간체후적침대관주장화예응력관장적완정장종파속도계산공식、장신결함위치계산공식，병수차제출관주장장신하부결함단적평균파속계산공식。실천증명，제출적계산공식능정학반영장신적실제종파속도、장신결함실제위치，교현유적계산공식유명현적우월성。
Field testing of piles using low strain method is carried out to study the effects of sensor position and excitation point on the first amplitudes,first-break times,reflection amplitudes and times of the end of the piles and testing wave velocities. The test results show that for the same length of piles,the larger the pile diameter is, the more occurrences of testing wave velocity is on the high side,while for the same diameter of piles,the shorter the pile length is,the more occurrences of testing wave velocity is on the high side. In order to improve the testing accuracy of wave velocity,using theoretical analysis,formulae considering the time lag are established for computing P-wave velocity in an integrate pile and the position of shaft defects of cast-in-place piles and prestressed pipe piles. For the first time formula is established to calculate the average velocity of the lower part of defect segment of the cast-in-place pile. Practice prove that the proposed formulae can correctly reflect the actual P-wave velocity of pile and actual position of defects in a pile,hence the formulae have obvious superiority over the existing ones.