Method and apparatus for measuring depth of crack for reinforced concrete construction

摘要

By arranging a pair of an ultrasonic wave transmitting sensor and an ultrasonic wave receiving sensor in opposition across a crack in a reinforced concrete construction. An ultrasonic wave is transmitted from the ultrasonic wave transmitting sensor at a first position. A reflected wave is then received by the ultrasonic wave receiving sensor at the first position. Also, the ultrasonic wave is transmitted from the ultrasonic wave transmitting sensor at a second position. A reflected wave is then received by the ultrasonic wave receiving sensor at the second position. The received waves at two positions are provided mutual phase shift for a predetermined period and summed in reversed phase for deriving a rise time of the wave reflected from the crack. By this, even when reinforcement is arranged in the concrete, the noise component superimposed on the received wave due to presence of the reinforcement can be eliminated to permit high precision measurement of the depth of the crack irrespective of the presence of the reinforcement at high density.