To solve the problem that not only a mesh-clogging substance of drain pipe but also natural ground loosened into earth and sand by weathering are sucked and remain in a pipe by a siphon phenomenon when flowing out with water jectted in a large quantitie in a conventional high pressure cleaning construction method. 従来の、高圧洗浄工法では、水抜きパイプの目詰まり物質だけでなく、風化でゆるみ土砂化した地山まで削り、大量に噴射した水で、流れ出る際にサィホン現象で土砂までパイプ内に吸い込み残留する。 - 特許庁