Device for modifying a layer of granular medium

A device configured to be disposed within a granular medium, such as sand or sediment, to raise a layer of said granular medium, the device comprising:

• a flexible envelope forming an internal volume;
• at least one inflatable element housed in the internal volume so as to be interposed between an upper surface and a lower surface of the envelope, the inflation and deflation of said element allowing the internal volume to be varied;
• an injection device configured to fill the inflatable element with a fluid;
• the device being configured to switch from a first configuration in which the inflatable element is inflated to occupy a first volume to a second configuration in which the inflatable element is inflated to occupy a second volume greater than the first volume so that the upper surface is deformed vertically in order to raise the layer of granular medium, and vice versa;
• the device being configured so that the lower surface remains substantially horizontal in the first and second configurations in order to maintain the device in position in the granular medium;
• the device further being configured to switch from the first or the second configuration to a third configuration in which the lower surface of the envelope is vertically deformed for allowing the device to ascend through the granular medium.