Geomembrane bag sand blowing cofferdam

The utility model relates to a geomembrane bag sand blowing cofferdam which comprises geomembrane bags with different lengths, and a positioning steel pipe support, wherein the bottom end of the positioning steel pipe support is inserted into the river bed surface around a bearing platform planned to be constructed, and the geomembrane bags are sequentially stacked in sequence from long to short to form an enclosed body which is closed and provided with a trapezoid transverse end face in the space inside the positioning steel pipe support. The requirement for cofferdam construction accuracy is not high, a plurality of underwater foundations can be defined and formed at a time, applicability is strong, the technology is simple, the environment is protected, the geomembrane bag sand blowing cofferdam can be widely applied to underwater structural objects which are placed where the depth of water is less than 5 meters, ripraps and boulders exist in the river bed, topographic change is large and environmental protection requirements are high.