Abstract
A non-contact and non-destructive geotechnical exploration method is proposed to detect underground cavities in the back of the concrete wall structure by measuring the temporal variations of the wall surface temperature using the infrared camera. The experimental and numerical analyses are conducted to verify the applicability of this method. The results show that the underground cavities covered by the concrete plate which has a thickness thinner than about 10cm can be detected by the temporal variations of the spatial temperature distribution based on the thermal images of the plate surface captured by the infrared camera.