| 摘要 |
PURPOSE:To exactly measure the amount of penetration of the legs of a jack-up type offshore structure by providing a draft meter to measure the draft of the structure, a torque meter to measure torque acting on a jack for lowering the legs, a stroke meter to measure the sending-out amount of the legs and a sonar to measure the distance to the seabed. CONSTITUTION:A leg 12 is brought down from an offshore structure body 11 and landed on the seabed, whereupon the torque becomes maximum and the measured values LS0 and LD0 of a stroke meter 17 and a draft meter 18 are then put in a penetrating amount arithmetic unit 22. The penetrating amount Lpn of the leg 12 until the draft height of the body 11 becomes zero is LPn=LSn- LS0-(LD0-LDn), where Lsn is the penetrating amount of the leg, LDn is draft height, LS0 is the sending-out amount of leg when landing on the seabed, and LD0 is draft height of leg when landing of the seabed. After the body 11 is lifted up to the sea surface and the draft height LDn becomes zero, a sonar 19 is brought down into the sea and the penetrating amount of the leg 12 is then LPn=LSn- l3-l2, where l3 is the lowering distance and l2 is the distance to the seabed, measured by the sonar. |
