Abstract：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.
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HU Xinfa，LIU Jianxin. STUDY OF INACCURACY OF P-WAVE VELOCITY IN PILES BY LOW STRAIN INTEGRITY TESTING. , 2013, 32(s2): 4183-4189.
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2013, Vol. 32 
