System for driving open end pipe piles on the ocean floor using pneumatic evacuation and existing hydrostatic pressure

Abstract

A new pile assembly is disclosed. It comprises an open end pipe pile (a cylindrical pipe pile provided with a pile cap) that is provided with: (1) a diaphragm adapted to slide axially within said open end pipe pile; (2) a conduit that allows gases and liquids to flow to and from the upper portion of the interior of said open end pipe pile through a conduit port; and (3) a one-way valve that allows gases and liquids to flow from an inlet port (that is below said conduit port) in the interior of said open end pipe pile to an exhaust port on the exterior of said open end pipe pile. The preferred embodiment of the invention also comprises: (4) an open end pipe pile with a lower end of reduced interior diameter; (5) means for retaining drilling mud in the lower portion of said open end pipe pile; and (6) a flexible riser in the interior of said open end pipe pile that provides a passageway for liquids and gases from said inlet port to said one-way valve. A new process for driving an open end pipe pile into the sea floor at significant depths below the ocean surface is also disclosed. It comprises the steps of: (1) displacing liquid from the interior of an open end pipe pile (that has initially penetrated the sea floor) to the ambient by forcing compressed gas into the upper portion of said open end pipe pile; and (2) evacuating or venting said compressed gas from the upper portion of said open end pipe pile to the atmosphere thereby causing said pile to be driven by existing hydrostatic pressure. In the preferred embodiment of the process, the hydrostatic pile driving is done in a plurality of stages, with each stage comprising said steps (1) and (2). The preferred embodiment of the process also comprises the use of drilling mud: to provide lubrication between the diaphragm and the interior surface of the pipe pile, and between the exterior surface of the soil core and the interior surface of the pipe pile; and to give additional weight to the pile assembly thereby increasing the initial penetration of the sea floor, and preventing piping during the hydrostatic pile driving of step (2).

Dependencies are inferred from the claim text.