Loose soil, rock, concrete structures, etc., measuring device and cracking range measurement method

摘要

PROBLEM TO BE SOLVED: To ensure an accurate measurement by inserting ultrasonic measuring units in holes made in the outer circumferential surface in a cavity at a plurality of measuring points and measuring the range of slack or crack in the ground from the difference of measured ultrasonic velocity thereby eliminating restriction in the measuring direction. SOLUTION: Ultrasonic measuring units 3 are inserted sequentially into a plurality of anchor holes or boring holes 2 made in a cavity, e.g. a tunnel or a basement. A stopper 9 is stretched on the outer surface of the anchor hole or boring hole 2 so that the anchor hole or boring hole 2 can be stopped at a measuring point even if it elongates vertically upward. An ultrasonic transmitter 4 is then actuated to transmit an ultrasonic wave which is received by an ultrasonic receiver 5. An ultrasonic velocity detector 12 detects the velocity of an ultrasonic wave from a received ultrasonic wave group and an indicator 13 indicates the velocity for each depth of the hole thus recognizing a slack or crack in the ground. When a decision is made that the slack in the ground is localized, an accurate measurement can be performed by limiting the fixing interval of the ultrasonic transmitter 4 and the ultrasonic receiver 5.