METHOD OF MEASURING OPEN CRACK DEPTH OF CONCRETE SURFACE

摘要

PURPOSE:To accurately measure the depth of the crack opened on a concrete surface in real time by receiving the ultrasonic wave which is emitted from a probe for transmission and returns by diffracting the front end of the depth of the above-mentioned crack, by a probe for reception. CONSTITUTION:The normal probes 12, 13 for transversal waves for transmission and reception are disposed to face each other on both sides of the opened crack 14 and are pressed onto the same plane 11a of the concrete 11 which is an object to be inspected. The SH transversal wave of the low frequency from the probe 12 is projected on the concrete 11. The propagation route and propagation distance before the incident SH transversal wave is received by the probe 13 are determined as a parabola 16 passing the three points from the center of the contact face of the probe 12 through the front end of the depth of the crack 14 up to the center of the contact face of the probe 13, then the propagation time of the SH transversal wave with respect to the propagation distance is determined by using the prescribed equation. The depth of the opened crack 14 on the concrete surface 11a is measured by the correlation between the propagation time and the depth of the crack 14 obtd. in such a manner.