Abstract
The dike based on the peaty soft ground at Ishikari River down stream has some weak points. It is the looseness and the cavity etc. Dike disaster occurred a collapse and 42 places slope sliding around the slice at the time of flood of August, 1981. That is why the way of the ensuring safety of consecutive dikes became the problem.
The purpose of this paper is prevention of collapse and damage reduction around the sluice which is essential to the ensuring safety of the community. First of all, I spoke the need of certain safety from factor grasp of the differential settlement and a trend of flood plain development and the dike maintenance. To the second, I suggested the investigation method, after having clarified a form of the transformation and progress of the differential settlement and these risk based on a field works. To the third, I estimated the progress form that a dike reached the breaching and showed the way of lasting measures in consideration of the form and outbreak range. Thereafter, I performed consideration for establishment of the general safety measures technology.
