DEVELOPMENT OF THE NEW INSPECTION METHOD ON SCOUR CONDITION AROUND EXISTING BRIDGE FOUNDATIONS

In the past, investigation on the scour condition around bridge foundations in Japan has been conducted by the traditional method which is to measure a depth from water surface to streambed by using a standing bar on a boat. However, it has been difficult to measure the precise depth through this method. Now the Public Works Research Institute has a newly developed method that measures depth by a radio-controlled boat with an acoustic analysis device and a personal computer analyzing data collected in combination with its location. According to the method, ups and downs of streambed around a pier can be two-dimensionally and precisely measured. A method based on the relatively simple principle for survey of the progressive condition at streambed during floods has also been developed.