RU2280931C1 - Underwater cable laying method - Google Patents

Abstract

FIELD: laying electric service lines across water obstacles.

SUBSTANCE: proposed method involves cable laying in plastic pipeline. To this end plastic pipes are first welded together on land with cable and ground wire or wires gradually drawn through them; then pipeline incorporating cable and ground wire or wires is pushed to water and conveyed toward transition point on bank. Pipe is secured on bank for movement and transported to opposite laying point with reference to pre-installed buoys at the same time arranging it on underwater route. Upon fixation of other end of pipe for displacement this pipe is unsealed for water admission therein, gradually laid on bottom, and secured thereon.

EFFECT: reduced anthropogenic impact time, ability of protecting underwater communities of water reservoir.

4 cl, 2 dwg

Description

The invention relates to the laying of an electric cable through water obstacles.

A known method of laying cables and polyethylene pipelines through the coastline, in which the cable and polyethylene pipelines are passed through a casing polyvinyl chloride pipe, drawn through a network communication well pre-drilled from land [Patent 2164050, Russian Federation, IPC ⁷ Н 02 G 1/10, Н 02 G 1/08, F 16 L 1/00. The method of laying cables and polyethylene pipelines underground through the coastline / Filimonov S.I., Shakhov A.V. - Publ. 2001.03.10].

A known method of laying cables and polyethylene pipelines underwater, including the simultaneous development of trenches, laying of cable and polyethylene pipelines, as well as the washing of trenches [Patent 2165121, Russian Federation, IPC ⁷ Н 02 G 1/10, Н 02 G 1/06, Н 02 G 9/02, E 02 F 5/00. A method of laying cables and polyethylene pipelines under water below the bottom of the reservoir and a device for its implementation / Filimonov S.I. - Publ. 2001.04.10].

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 need to lay a cable line for powering the island of Olkhon on Lake Baikal has been discussed for decades.

Laying of underwater cables in reservoirs of any type is always associated with a negative impact on underwater biocenoses, the extent of damage to which is often not comparable with the economic benefits of operating cable lines.

The objective of the invention is to lay a cable line for power supply of the island with minimal environmental threats to the ecosystem of Lake Baikal, a unique World Natural Heritage Site, replete with endemic species of underwater flora and fauna.

Currently, the violation of underwater biocenoses in the areas of the mainland and island marinas of the Maliy Olkhonsky Gates Strait, through which the cable is laid, has reached significant values. 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 potential of the food base for ichthyofauna.

The technical result of the claimed invention is to reduce environmental damage to the ecosystem of Lake Baikal, reduce the time of laying the cable, reduce the turbidity spot when laying it, increase the safety of electromagnetic fields on the ichthyofauna of the lake 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 they weld the plastic pipes with a gradual pulling of the cable and cable inside them. The resulting pipe design with a cable and cable laid in them is hermetically sealed at both ends. The pipe thus prepared is pushed into the water and transported to the coastal point of the transition point. Here, the pipe is attached to the cable on the shore with the possibility of movement and transported along previously placed buoys to the opposite point of the laying place, distributed along the route of the underwater laying, after which the other end of the pipe is fixed on the shore with the ability to move it along the route line and the necessary rotation 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.

With a cable can stretch two or more cables. 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, for example, using bags of cement.

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.

Figure 1 shows the cable in the pipe on the surface of the water and the beginning of laying the pipe with cable, figure 2 - cable laid on 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 during laying it to the bottom. Position 3 - a plastic pipe filled with water with a cable in the working position after installation.

Example.

Billets of polyethylene black pipes with a diameter of 315 mm with a total length of 3.5 km are brought to the berth area on the Olkhon coast. 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 preferable to use a cable similar to that produced by the company "Nexans" (Germany). 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.

Cable laying technology uses pressure pipes made of low-pressure polyethylene PE 80 SDR 26-315 · 12.1 (5 atm).

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 equal to 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. Pipes are delivered to the assembly place with 12 m lengths. It is possible to use pipes мм 355 mm with wall thickness up to 24 mm, withstanding pressure up to 10 atm.

Pipes are welded on the shore and a cable and two cables are gradually pulled into them, one fastened with a cable, the other free. The pipe is welded with special welding machines.

When working in two shifts, welding is carried out in seven days. Two pipes with cable and cables, each 1.7 km long, are being prepared at the same time. The length of the cables is 200 meters longer than the length of the plastic pipe.

The finished pipes from both ends are sealed to prevent water from entering them. Then one pipe is pushed along the entire length into the water, taken away from the cable on one side and transported by ship to the coastal point of the main part of the passage. 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 when the structure is oriented during work. With the help of two ships, the structure is distributed along the placed buoys along the route of the underwater gasket and the other end of the pipe is fixed on the other (Olkhon) bank also with the possibility of moving 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, prepared as described above, is laid parallel to the first at a distance of 20-50 m from it.

The proposed technology of cable laying causes minimal damage to the underwater communities due to short-term negative impact produced only in the process of lowering and laying the cable to the bottom. A significant decrease in the turbidity spot occurs and, as a result, the balance of biological communities is maintained.

The application of the method significantly reduces the construction time.

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

Claims (4)

1. A method of laying an underwater cable, including laying a cable and a plastic pipe, characterized in that the plastic pipes are welded first on land with a gradual pulling of the cable and cable inside them, then the resulting pipe structure with the cable and cable laid in them is hermetically closed from both ends , pushed into the water and transported to the coastal point of the transition point, where the pipe is mounted on the shore with the possibility of movement and transported by previously placed buoys to the opposite point of the place okladki distributing the track laying underwater, and then fix the other end of the pipe to be movable along its track lines produce pipes and gradual depressurization laying on the bottom when filling the tubes from the water tube fixation of laying on the bottom. 2. The method according to claim 1, characterized in that two or more cables are pulled with a cable, while one of them is connected to the cable. 3. The method according to claim 1 or 2, characterized in that the cable is laid in a plastic pipe, gradually filling the plastic pipe with water from one end, and fixing the pipe into two is carried out pointwise, at certain intervals. 4. The method according to claim 3, characterized in that the fixation of the pipe at the bottom is carried out using bags of cement.

Images