Port of Patras

November 2000 at Greece


Method Applied

Bottom Feed Stone Columns

In the 1900ies soil liquefaction caused by an earthquake destroyed parts of the Port of Patras, it needed therefore no convincing to install stone columns for liquefaction mitigation on this project.

The underwater receiver tank with “schnorchel hose” for the pressure discharge of excess stone transport air to the surface was invented in 2000 by Alexander and Wilhelm Degen. The patent is valid in some countries and today held by others.

For sites in deep waters in relation to the soil treatment depth, this system allows the classic double lock gravel pump to pneumatically transport the stones into an underwater receiver without counteracting water pressure while a receiver above water traditionally simply releases the excess air via a short tube or a venting cover on top of the receiver.

Current new developments like water transport of the stones can avoid the relatively expensive pneumatic stone transport. The patented air discharge hose is nowadays obsolete.