Interesting idea and putting the safety aspect of the open chain drive and revolving helical tubes to one side the tubes obviously act as floats stopping it from sinking in and it does seem to work but is really just for snow and ice.
The Russians built something similar (Zil 2906) in case they had to go find astronauts in inaccessible places.
Video on youtube -
http://www.youtube.com/watch?v=afJ18eJeNgU
The UK/USA came up with another idea during WW2 but it turned into a tracked vehicle
http://en.wikipedia.org/wiki/Screw-p...rld_War_period