CN112134220A

CN112134220A - Landing section submarine cable traction construction method under small tidal range condition

Info

Publication number: CN112134220A
Application number: CN202010875606.5A
Authority: CN
Inventors: 柴宝亮; 郭卫兵; 张年华
Original assignee: Searaise Energy & Technology Beijing Co ltd
Current assignee: Searaise Energy & Technology Beijing Co ltd
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2020-12-25

Abstract

The invention relates to the technical field of submarine cable laying, and discloses a submarine cable pulling construction method for a landing section under a small tidal range. The construction method comprises the following steps: 1) in the temporary laying process of throwing the submarine cable on the ship to the seabed in a continuous S-turn manner in a preset area by the cable laying ship, binding a certain size of floating-assistant floating body on the submarine cable at intervals of a plurality of distances; 2) in the pulling process of landing submarine cables, the buoyancy provided by the floating-assistant floating bodies is used for overcoming the weight of part of submarine cables, so that the friction force between the submarine cables and the seabed is reduced; 3) after landing the submarine cable and pulling in place, under the assistance of a small ship, constructors cut off the rope connection between the floating-assistant floating body and the submarine cable and recover the floating-assistant floating body. The invention provides a construction solution for dragging the submarine cable at the landing section under the condition of small tidal range, so that the dragging force for dragging the submarine cable is greatly reduced, the protection of a surface layer and an internal structure of the submarine cable is facilitated, and the model selection of dragging equipment is facilitated.

Description

Landing section submarine cable traction construction method under small tidal range condition

Technical Field

The invention relates to a submarine cable laying technology, in particular to a submarine cable pulling construction method at a landing section under a small tidal range.

Background

The landing-section submarine cable is paved with two conditions of self-sea-to-land laying and self-land-to-sea laying. For the case of laying from sea to land, the basic construction steps are: 1) the cable laying ship carries out S-turn temporary laying in a preset area by utilizing a high tide period, namely, the residual sea cables on the cable laying ship are thrown onto the seabed of the preset area and are in a regular and continuous S-turn state; 2) connecting the end part of the submarine cable with shore pulling equipment through a steel wire rope; 3) starting a pulling device to pull the end part of the submarine cable to a preset position, and simultaneously straightening the submarine cable in a continuous S-shaped bent state along a cable design route; 4) the submarine cable is buried below the seabed to a designed depth.

The selection of the predetermined area for temporary laying of the S-turn by the laying vessel is related to the draught of the laying vessel. The water depth of the preset area at high tide not only meets the requirement of more than the draught requirement of the residual cable carried by the cable laying ship, but also meets the requirement of the time required by the cable laying ship to carry out S-turn temporary cable laying operation by ship moving in the area. The tidal range is large, and the beach exposure time in a preset area is long, such as the tidal range is larger than 3.5m, and the beach exposure time is usually more than 4.5 hours; conversely, the tidal range is small, and the open time in the predetermined area is short, such as the tidal range is less than 1.5m, and the open time is usually below 1.0 hour. The size of the tidal range of the predetermined area is a primary factor that characterizes how long the predetermined area has been exposed to the beach.

For sea areas with large tidal ranges, the beach exposure time of the predetermined area is longer after the ebb tide is removed. In this case, the friction between the submarine cable and the seabed can be reduced by lifting and moving the submarine cable by using a plurality of excavators, and the dragging equipment can be assisted to drag the submarine cable. However, in the sea area with small tidal range, the time for exposing the water surface in the preset area after the tide is removed is short, and the excavator is not enough to be used for matching with the pulling operation of the submarine cable on the mudflat.

Therefore, the technical problem that submarine cable laying construction cannot be avoided is to find a solution for submarine cable pulling construction at the landing section under a small tidal range condition.

Disclosure of Invention

In order to solve the problem of pulling construction of the landing section submarine cable under the condition of small tidal range, the invention provides a pulling construction method of the landing section submarine cable under the condition of small tidal range, which is characterized by comprising the following steps:

(1) in the temporary laying process of throwing the submarine cable on the ship to the seabed in a continuous S-turn mode in a preset area by the cable laying ship, a certain size of floating-assistant floating body is bound on the submarine cable at intervals of a plurality of distances.

(2) In the pulling process of the landing submarine cable, partial weight of the submarine cable is overcome by buoyancy provided by the floating-assistant floating body, so that the friction force between the submarine cable and the seabed is reduced.

(3) After landing the submarine cable and pulling in place, under the assistance of a small ship, constructors cut off the rope connection between the floating-assistant floating body and the submarine cable and recover the floating-assistant floating body.

The size of the floating-assistant floating body and the binding distance on the submarine cable are determined according to the unit length weight of the submarine cable, the size of the traction resistance and the size of the transverse ocean current, so as to reduce the friction force between the submarine cable and the seabed and prevent the submarine cable from transversely drifting, and the principle that the floating-assistant floating body overcomes 70-85% of the gravity of the submarine cable is adopted.

The floating-aid floating body is preferably made of a material which is not easy to compress.

The invention has the beneficial effects that: provides a construction solution for pulling a submarine cable at a landing section under a small tidal range. The submarine cable is pulled in a semi-suspension state in seawater, so that the contact friction between the submarine cable and a seabed is greatly reduced, the protection on a submarine cable surface layer is facilitated, the traction force for pulling the submarine cable is greatly reduced, and the damage of the overlarge traction force on a submarine cable structure is avoided; meanwhile, the lower traction force is convenient for the type selection of the traction equipment.

Drawings

The following detailed description is to be read in connection with the accompanying drawings and the detailed description.

FIG. 1 is a plan view of the present invention prior to cable pulling;

FIG. 2 is a schematic view of the floating-aid buoy tied on a sea cable;

fig. 3 is a layout view of the submarine cable after being pulled.

Wherein: 1-a predetermined area; 2-sea cable; 3-floating-assistant floating body; 4-a pulling apparatus; 5-a steel wire rope; 6-pulling the net cover; 7-the seabed; 8-high tide line; 9-water level; 10-a rope.

Detailed Description

As shown in fig. 1, the submarine cable is buried while being laid on the side of the cable laying vessel, and after reaching a predetermined area 1, the submarine cable on the vessel is thrown onto the seabed 7 in a continuous S-turn temporary laying state. The temporary laying of the submarine cable means that the submarine cable 2 is laid on the seabed 7 without being buried. In the process of putting the submarine cable 2 into water, a certain size of floating-assistant floating body 3 is bound on the submarine cable 2 at intervals of a plurality of distances.

As shown in fig. 1 and 2, the wire rope 5 led out from the pulling device 4 located above the high tide line 8 is pulled to the end of the submarine cable 2 and connected with the end of the submarine cable 2 through the pulling net 6. During the landing and pulling process of the submarine cable, the buoyancy provided by the floating-assistant floating body 3 overcomes part of the weight of the submarine cable 2, so that the friction force between the submarine cable 2 and the seabed 7 is reduced.

As shown in FIG. 2, for a submarine cable 2 with a diameter of 250mm, the weight in the air is 110kg/m, the weight in the water is 49kg/m, and the maximum allowable traction force is 520 kN; the floating-assistant floating body 3 made of the material which is 500mm in diameter and 1000mm in length and is not easy to compress can provide 175kg of buoyancy, one floating-assistant floating body 3 is bound on each 2.3m of the submarine cable 2, and 80% of the gravity of the submarine cable can be overcome. For an S-bend cable 2 of 1000m length, the calculated maximum pulling resistance is 48kN, so that a pulling device 4 with a pulling force of 100kN can be selected to meet the requirement.

As shown in fig. 3, after the submarine cable is landed and pulled in place, the constructor cuts off the floating-assistant floating body 3 below the water surface 9 and connects with the rope 10 of the submarine cable 2 with the help of the small-sized ship, and recovers the floating-assistant floating body 3.

Claims

1. The construction method for pulling the submarine cable at the landing section under the condition of small tidal range is characterized by comprising the following steps:

(1) in the temporary laying process of throwing the submarine cable on the ship to the seabed in a continuous S-turn manner in a preset area by the cable laying ship, binding floating-assistant floating bodies with certain sizes on the submarine cable at intervals of a plurality of distances;

(2) in the pulling process of landing submarine cables, the buoyancy provided by the floating-assistant floating bodies is used for overcoming the weight of part of submarine cables, so that the friction force between the submarine cables and the seabed is reduced;

2. The method for pulling and constructing the submarine cable at the landing section under the condition of small tidal range according to claim 1, wherein the size of the floating-assistant floating body and the binding distance on the submarine cable are determined according to the unit length weight of the submarine cable, the pulling resistance and the transverse ocean current, so as to reduce the friction force between the submarine cable and the seabed and prevent the submarine cable from transversely drifting, and according to the principle that the floating-assistant floating body overcomes 70-85% of the gravity of the submarine cable.

3. The method for pulling and constructing a submarine cable at a landing section under a small tidal range according to claim 1, wherein the floating-aid floating body is preferably made of a material which is not easily compressed.