堤内地漏水孔(ガマ)への浸透現象に関する研究

Abstract

A phenomenon of spouting a seepage water with soil particles out from a hole, perforating a top stratum landward of a dyke, was studied in this paper. Approaches of three steps to accomplish this study were adopted, such as laboratory tests, 3-dimensional FEM analyses and 2-dimensional theoretical solutions to well problems. The laboratory tests were performed in order to investgate the critical difference of the water-level between the river and the hole against the spouting phenomenon. The FEM analyses were applied to the critical states as mentioned above to search the critical hydraulic gradient taking the soil particles into the hole, and the velocity taking the soil particles out of the hole. Measured pressure heads in the laboratory tests showed a good agreement with the calculated results by FEM analyses. The theoretical solutions were compared with the ones obtainde FEM analyses for the purposes of finding out of the relations between both. It was concluded that 2-dimensional theoretical solution to a well problem can be available to evaluating the possibility of occurring of spouting out phenomenon from the practical hole in the top stratum landward of the dyke.