Development of AE counting system and it's application to monitoring of ground behavior

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The researchers developed a simple AE monitoring system which records only rate count corresponded with AE wave over a threshold. This is to be able to automatically record for a long term (i.e. more than 400 days) by battery power without a computer.This system is made economically and so we can use many systems in field. One system is composed of two amplifiers and AE sensors. That is, the characteristic point of the system is to adopt an active-dummy method for a noise of AE signal. In AE measurements, especially in the field, it is not so easy to distinguish any noise from recorded signals. Therefore, an active AE sensor is directly attached onto a rock or a wave-guide while a dummy sensor is not attached onto them. If an AE count is recorded at the same time in active and dummy sensors simultaneously, the active count is cancelled from the record for a given time interval. These AE counting systems were applied to many fields and underground structures in Japan, Turkey and Egypt.For example, for about sixty years, a town called Babadag in Turkey has been suffering from a landslide. Babadag is located about sixty kilometers far from Denizli City. The main part of this town is located on a horst-like hill. Two small creeks situated on the east and west limit the area of the town. The elevation of the town is about 700 meters. In this twon, we installed the AE system, ground surface deformation through hand-held laser distancemeter, pipestrainmeter, ground water level, rainfall, temperature and humidity.According to comparison with each other's parameters obtained by these integrated monitoring systems, it is shown that AE activities well corresponded to the surface movement of the landslide and the amount of rainfall. Especially, it is obvious that there a time lag between the AE activities and the rainfall. These time lag were observed in many Japanese fields.This AE monitoring system developed by the project has enough practicality in field.