Method for treating an underwater bed

• US 6,874,261 B2
• Filed: 04/07/1995
• Issued: 04/05/2005
• Est. Priority Date: 04/07/1994
• Status: Active Grant

• Current Assignee: Van Oord Nv (Merweoord BV)
• Original Assignee: Van Oord Nv (Merweoord BV)
• Inventors: Smit, Paul, Schuit, Adrianus Jacobus Petrus Marinus
• Primary Examiner(s): Will, Thomas B.
• Assistant Examiner(s): Beach, Thomas A.
• Application Number:
  US08/718,573
• Publication Number:
  US 20030056403A1
• Time in Patent Office: 3,651 Days
• Field of Search: 373/23, 373/07, 373/35, 373/44, 373/34, 373/22, 373/36, 373/42, 405/163, 405/248
• US Class Current: 37/307
• CPC Class Codes: E02F 3/88 with arrangements acting by a sucking or forcing effect, e.g. suction dredgers pumps in general F04
• CPC Class Codes: E02F 3/905 Manipulating or supporting suction pipes or ladders; Mechanical supports or floaters therefor; pipe joints for suction pipes for heave compensation E02F9/067 takes precedence; pipelines per se E02F7/10; joints for pipes in general F16L
• CPC Class Codes: E02F 3/9206 Digging devices using blowing effect only, like jets or propellers E02F5/107 takes precedence; passive suction heads with jets E02F3/925; active suction heads with jets E02F3/9262; drilling by jets E21B7/18; slitting by jets E21C25/60
• CPC Class Codes: E02F 5/104 for burying conduits or cables in trenches under water floating substructures per se E02F9/06
• CPC Class Codes: E02F 5/107 using blowing-effect devices, e.g. jets digging devices using a blowing effect per se E02F3/9206
• CPC Class Codes: E02F 5/108 using suction-effect devices suction heads per se E02F3/9243, E02F3/9256

Abstract

A method of forming a trench in the bed of a body of water, the bed having an initial undisturbed upper surface, comprises suspending a pressure line from a vessel floating on the body of water, the pressure line terminating downwardly in a downwardly directed nozzle. The nozzle is positioned a small distance above the bed, and water is pumped under pressure on board the vessel and is discharged via the pressure line and nozzle downwardly against the bed surface with the water pumped at an overpressure between 0.01 bar and 20 bar and at a flow rate of 0.25 to 20.0 cm per second. The distance of the nozzle above the surface of the bed is not more than ten times the diameter of the water jet defined by the nozzle, preferably about six times the diameter of that water jet.

Claims

1. A method of forming a trench in the bed of a body of water, said bed having an initial undisturbed upper surface, comprising suspending a pressure line from a vessel floating on said body of water, said pressure line terminating downwardly in a downwardly directed nozzle, positioning said nozzle a distance above said bed, pumping water under pressure on board said vessel and discharging said water via said pressure line and said nozzle downwardly against said surface with said water pumped at an overpressure between 0.01 bar and 20 bar and at a flow rate of 0.25 to 20.0 cm per second, while maintaining said nozzle positioned at said distance above said bed.

2. A method as claimed in claim 1, wherein said distance is not more than ten times the diameter of the water jet defined by said nozzle.

3. A method as claimed in claim 1, wherein said distance is about six times the diameter of the water jet defined by said nozzle.

4. A method as claimed in claim 1, wherein the water is pumped at an overpressure between 0.01 bar and 8 bar.

5. A method as claimed in claim 1, wherein said nozzle has an internal diameter of 0.1 to 5 meters in size.

6. A vessel as claimed in claim 1, wherein said nozzle has an internal diameter of 0.2 to 3.0 meters in size.