LIQUID DETECTION SENSOR, MOISTURE DETECTION SENSOR, DETECTION OF PERMEATION OF MOISTURE INTO SOIL AND MOISTURE DETECTION APPARATUS

摘要

PROBLEM TO BE SOLVED: To predict the break of a bank at an early stage by emitting ultrasonic waves to the moisture absorbing member inserted into the space of a member having a water leak type perforated part to detect reflected waves. SOLUTION: Water leak type perforated part 5 are regularly provided to the periphery of a column or square pillar-shaped pipe 1 and a moisture absorbing member 2 is inserted into the internal space of the pipe 1. A bottom plate 3 is provided to the lower end of the pipe 1 and a piezoelectric part 4 is provided to the upper surface thereof. The perforated parts 5 are used, for example, by vertically embedding the pipe in soil so that the bottom plate 3 is turned downward. The perforated part 5 takes in moisture in soil being in contact with the pipe 1 to allow the same to penetrate into the internal absorbing member 2 and the moisture accumulated in the absorbing member 2 is drained to the outside from a plurality of the holes 3A of the bottom plate 3. The absorbing member 2 is different in the propagation and reflecting characteristics of ultrasonic waves corresponding to the penetration degree of moisture. The piezoelectric part 4 emits ultrasonic waves to the absorbing member 2 and detects reflected waves to output an electric signal. This signal is monitored and analyzed to make it possible to grasp a moisture penetrated state. By this constitution, the early prediction of the break of a bank or the collapse of a precipice becomes possible.