Underwater excavation apparatus

摘要

There is disclosed an underwater excavation apparatus (2) comprising mass flow excavation means (4) and jet flow excavation means (6). The mass flow excavation means (4) causes a mass flow at a pressure less than that of a jet flow of the jet flow excavation means (6). The mass flow excavation means (4) causes a mass flow at a volume flow rate greater than that of a jet flow volume rate of the jet flow excavation means (6). An outlet (16) of the jet flow means (6) is provided within an outlet (18) of the mass flow means (4).