WO2006054917A1

WO2006054917A1 - Method for lying an underwater cable

Info

Publication number: WO2006054917A1
Application number: PCT/RU2005/000500
Authority: WO
Inventors: Alexander Nikolaevich Suturin; Viktor Vasilievich Minaev
Original assignee: Limnologichesky Institut Sibirskogo Otdeleniya Rossiiskoy Akademii Nauk
Priority date: 2004-11-18
Filing date: 2005-10-06
Publication date: 2006-05-26
Also published as: RU2280931C1; RU2004133793A

Abstract

The invention relates to laying electric communication networks through water bodies. The inventive method provides for laying the cable into a plastic pipeline and consists in welding plastic tubes on land and in gradually drawing the cable thereinside by means of a rope or ropes or therewithout, in sealingly closing the thus obtainable cable-containing tube structure, shoving said structure into the water and in transporting the above to a waterside transition point, in movably fixing the tube to the land and in transporting it to an opposite laying point following pre-placed beacons along the underwater crossing. When the other end of the tube is movably fixed, the tube is unsealed and gradually laid down on a bottom, filled with water and is fixed to the bottom. Said method reduces a time of a man impact on a water body ecosystem, protects under water coenosis and substantially reduces the time an cost of cable laying.

Description

Method for laying submarine cable

Technical field

The invention relates to the laying of an electric cable through water obstacles, natural and artificial reservoirs.

BACKGROUND OF THE INVENTION There is a known method of laying cables and polyethylene pipelines through a coastline, in which a cable and a polyethylene pipelines are passed through a casing PVC pipe, drawn through a network communication well pre-drilled from land [Patent 2164050 Russian Federation, IPC ⁷ H 02 G 1/10, H 02 G 1/08, F 16 L 1/00. The method of laying cables and polyethylene pipelines underground through the coastline / Filimonov SI., Shakhov AB- Publ. 2001.03.10.] [1].

A known method of laying cables and polyethylene pipelines underwater, including the simultaneous development of a trench, laying cable and polyethylene pipelines, washing the trenches [Patent 2165121 Russian Federation, IPC ⁷ H 02 G 1/10, H

02 G 1/06, H 02 G 9/02, E 02 F 5/00. A method of laying cables and polyethylene pipelines underwater below the bottom of the reservoir and a device for its implementation / Filimonov SI.- Publ.

2001.04.10.] [2].

Known methods of laying cables through water barriers require the involvement of a large number of technical means and mechanisms, work with devices harmful to ichthyofauna, destruction of existing ecological communities in the bottom areas along the entire route.

Underwater laying of cable lines is associated with specific types of impact on the underwater environment. The impact has two components: temporary, associated with laying the cable, and permanent, due to the alienation of the territory and the impact of the electric cable on the hydrobionts. The main potentially dangerous type of anthropogenic impact on the ichthyofauna of a reservoir is the electromagnetic effect that occurs during the operation of a cable line.

Despite the fact that the history of laying submarine cables is almost two hundred years old, the problem of laying an electric cable through water barriers does not have an unambiguous solution. The laying of submarine cables in reservoirs of any type is always associated with a negative impact on underwater biocenoses; the extent of damage to ecosystems is often often not comparable with the economic benefits of operating cable lines.

SUMMARY OF THE INVENTION An object of the invention is to lay an underwater cable line for powering an object separated by a water barrier with minimal environmental threats to the reservoir ecosystem, preservation of endemic species of underwater flora and fauna.

For example, the necessity and possibility of laying a cable line for powering the Olkhon island on Lake Baikal has been discussed for decades.

Underwater construction, in particular, associated with the laying of communications in trenches, leads to disruption of underwater biocenoses in areas of the coastal line and at depths. A study of the route of the proposed electrical cable to solve the issue of energy supply of Olkhon Island revealed significant disruption of underwater biocenoses. Oil pollution of the water surface is noted, as a result of anchorage, bottom communities are disturbed. In the zone of cable laying are places of accumulation of industrially valuable fish. The territory for cable laying is located in the feeding zone of endemic fish and spawning grounds. Shallow coastal zones are characterized by great biodiversity. Investigations of the water turbidity spot at the place of laying the underwater cable showed that dusty particles with a diameter of 0.01 mm, swollen from the bottom and reaching the surface of the water, need 8 hours to settle to the bottom again. For medium sized dusty particles, it will take 3.5 hours. Small pelitic and clay particles (0.001 mm) will take 362 days.

The turbidity spot leads to a significant decrease in the productivity of phytoplankton and zooplankton, which are the initial link in the trophic chain. The decrease in water transparency due to turbidity leads to inhibition of phototrophic benthic aquatic organisms. Long-term maintenance of turbidity significantly worsens the conditions for the functioning of planktonic and benthic organisms and reduces the ability of the food supply for ichthyofauna. The technical result of the claimed invention is to reduce the environmental damage to the ecosystem of the reservoir, reduce the cable laying time, reduce the turbidity spot when laying it, increase the safety of electromagnetic fields on the ichthyofauna during cable operation, reduce the cost of work. The technical result is achieved by laying the cable and the plastic pipeline, while first, on the land, plastic pipes are welded with a gradual pulling of the cable inside them with or without a cable. The resulting pipe design with a cable inside is hermetically sealed at both ends. The pipe thus prepared is pushed into the water and transported to one of the coastal points of the transition point. Here the end of the pipe is mounted on with the possibility of moving along the previously arranged buoys, the gasket places are transported to the opposite coastal point, distributing on the water surface along the underwater gasket route, then the other end of the pipe is fixed on the shore with the possibility of moving it along the route line and the rotation necessary for laying along this line .

Then make the depressurization of the pipe and a gradual laying on the bottom when filling the pipe with water with the fixation of the stacked pipe at the bottom. When laying a cable line with a length of 3 km or more, two cables or more can be pulled with a cable. One of the cables is connected to the cable.

Cable laying in a plastic pipe is carried out, gradually filling a plastic pipe with water from one end, and fixing the pipe at the bottom is carried out precisely, at certain intervals.

Fixation of the pipe at the bottom is carried out using weights, which may be bags of cement, etc.

A cable for laying is used as a multicore cable with a system of protection against electromagnetic radiation. The plastic pipe for laying the cable in it has the characteristics of the material that are harmless to the environment, is black and opaque.

Conclusion of a conductive cable into the pipe serves as additional protection of the cable itself and the protection of the communities surrounding the cable from the electromagnetic field that occurs during operation. Brief Description of the Drawings

In FIG. 1. shows the cable in the pipe on the surface of the water and the start of laying the pipe with cable, in FIG. 2 - cable laid to the bottom.

Position 1 shows the cable in a sealed plastic pipe filled with air. 2 - cable after depressurization when lowering one end of the pipe into the water in the process of laying it on the bottom. Position 3 - water filled plastic pipe with cable in working position after installation.

BEST MODE FOR CARRYING OUT THE INVENTION Blanks of polyethylene black pipes of 0 315 mm with a total length equal to the length of the underwater route are brought to a coastal site in the area of the location of the proposed electric cable. A cable and cable drums are delivered to the same section.

The cable for laying is used three-core, with a symmetrical arrangement of conductive conductors and multi-layer protection against the emerging electromagnetic field. It is possible to use a three-phase geophysical cable of domestic production, subject to compliance with all protection elements. The system of protection of hydrobionts from the electromagnetic field is additionally strengthened by enclosing the cable in a plastic pipe.

In the cable laying technology, pressure pipes made of low-pressure polyethylene PE 80 SDR 26-315 * 12.1 (5 atm) are used. Pipes are delivered to the assembly place with 12 m lengths. It is possible to use 0 355 mm pipes with wall thicknesses up to 24 mm, withstanding pressure up to 10 atm.

The pipes are welded at the site and a cable and two cables are gradually pulled into them, one fastened with a cable, the other free. Pipes are welded with special welding machines.

Welding work can be arranged in two shifts. Two pipes are prepared at the same time with a cable and cables of equal length. The length of the cables is 200 m more than the total length of the plastic pipe. With a relatively short underwater track

(less than 3 km) there is no need to use a cable fastened with a cable.

The finished pipes from both ends are sealed to prevent water from entering them. Then they push one pipe along the entire length into the water, take it by the cable on one side and transport it to opposite coastal point of crossing point. Here the pipe is attached to the cable on the shore with the possibility of moving it along the longitudinal axis of the pipe and the necessary rotation at the attachment point for the necessary orientation of the structure in the right direction during the work. With the help of two ships, the structure is distributed along the arranged buoys along the route of the underwater laying. The other end of the pipe is fixed on the opposite bank also with the possibility of movement of the pipe for the necessary orientation in the process of laying the pipe with the cable to the bottom. Next, the pipe is depressurized and gradually lowered to the bottom, starting from one end, filling the pipe with water. A pipe filled with water is gradually laid at the bottom and fixed at the bottom with loads located at a distance of 30-50 m. Cement bags can be used as loads. The second pipe with cable, for the backup version, prepared as described above, is laid parallel to the first at a distance of 20-50 m from it.

To prevent biofouling, pipes must be made black and opaque. Polyethylene for pipes is used in accordance with the conclusion of the sanitary epidemiological service, compatible with food and environmentally friendly. The bearing capacity of the pipe is 67.5 kg / m. With the weight of the cable 18 kg / 1 m and steel cables 10 kg / 1 m, its buoyancy margin is at least 40 kg. The wall thickness of the pipe is 12.1 mm. The pipe withstands pressure of 5 atm or more and is not only an additional protection against physical influences that may occur during operation of the underwater cable, but also gives the effect of complete shielding of the electromagnetic field. Industrial applicability

The above method is laid cable line to the island of Olkhon on Lake Baikal. The cable is laid along the bottom of the strait

Small Olkhon Gate, while preserving the bottom communities of the ecosystem of Lake Baikal, a unique World Natural Heritage Site. The proposed technology of cable laying practically does not do any harm to underwater communities due to short-term negative impact produced only in the process of lowering and laying the cable to the bottom. There is a significant decrease in the turbidity spot and due to this the preservation of biological balance. Examination of the area of the laid pipe with cable showed that the habitat of goby fish and perch remained the same.

Fish take a laid pipe for a natural object.

The application of the method significantly reduces the construction time and reduces the cost of work due to the lack of the need for laying a trench and attracting a pipe with a cable for transportation and laying the construction of a conventional tugboat instead of a special cable laying vessel.

The inventive method of laying an underwater cable provides protection against weak electric fields, protects the spawning grounds, reduces the time of anthropogenic impact on the ecosystem of the reservoir, provides cable protection from physical, chemical and biological processes of destruction.

The method of laying an underwater cable is applicable for implementation in any, including deep, water bodies. Information sources

1. Patent 2164050 Russian Federation, IPC ⁷ H 02 G 1/10, H 02 G 1/08, F 16 L 1/00. The method of laying cables and polyethylene pipelines underground through the coastline / Filimonov SI., Shakhov AB- Publ. 2001.03.10.

2. Patent 2165121 Russian Federation, IPC ⁷ H 02 G 1/10, H 02 G 1/06, H 02 G 9/02, E 02 F 5/00. The method of laying cables and polyethylene pipelines under water below the bottom of the reservoir and a device for its implementation / Filimonov

SI.- Publ. 2001.04.10.

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Claims

Claim

1. A method of laying an underwater cable, including laying a cable and a plastic pipe, characterized in that the plastic pipes are first welded on land with a gradual pulling of the cable inside them with or without a cable, then the resulting pipe design with a cable inside is hermetically closed from both ends, they are pushed into the water and transported to one of the coastal points of the transition point, where the pipe is mounted on the shore with the possibility of movement and transported along previously placed buoys to the opposite shore chke napkin place, distributing the track laying underwater, and then fix the other end of the pipe to be movable along the line of its track laying underwater produce gradual depressurization pipe and laying on the bottom when filling the tubes from the water tube fixation of laying on the bottom.

2. The method according to p. 1, characterized in that two cables or more are pulled with a cable, while one of them is connected to the cable.

3. The method according to PP. 1 or 2, characterized in that the laying of the cable in a plastic pipe is carried out, gradually filling the plastic pipe with water from one end, and fixing the pipe at the bottom is carried out pointwise, at certain intervals.

4. The method according to p. 3, characterized in that the fixation of the pipe at the bottom is carried out using weights, which may be bags of cement, etc.

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