摘要
Based on the field low strain integrity testing for large diameter cast-in-place piles,the effects of the locations of sensor and excitation point on the first amplitudes and first-break times,reflection amplitudes and times of the end of the piles and testing wave velocities were obtained.Tests show that,for the same length of piles,the larger the diameter is,the more testing wave velocity is on the high side,while for the same diameter of piles,the shorter the length is,the more testing wave velocity is on the high side.In order to improve the accuracy of testing wave velocity,formulas for P-wave velocity in an integrate pile,for the location of defects in a pile and for the average velocity of defects in the lower section of the pile were obtainted,in which the time lag were concerned.Practice proves that the proposed calculation formulas can correctly reflect the actual P-wave velocity of pile,actual position of defects in a pile and the severity of the defect,and then have obvious superiority over the exiting ones.
