This application claims priority to Chinese Patent Application No. 202311382456.4, filed with the China National Intellectual Property Administration on October 24, 2023 and entitled "ULTRA-DEEPWATER SUBMARINE CABLE", which is hereby incorporated by reference in its entirety.

The present application relates to the field of deep-sea cable technology, and in particular, to an ultra-deepwater submarine cable.

In marine scientific expeditions, reeling winches and metal armored cables are commonly used to carry underwater submerses and detection devices to perform environmental exploration and resource sample collection in various areas of the ocean. In practical use, the metal armored cables not only withstands their own weight, but also are subjected to a dragging force from the underwater submerses, and the larger the water depth is, the larger the force applied to the armor layer is. At the same time, the corrosion failure of the armor layer in seawater will also exacerbate the risk of abyssal exploration failure.

The sea area with a depth greater than 6500 meters in the ocean is referred to as the abyss, and the abyss area accounts for 1.2% of the total ocean area and is one of the last unexploited areas by humans on the earth. As deep-sea oil and gas, deep-sea mining, and abyssal exploration move further into the deep sea, it becomes essential for a dynamic subsea photoelectric composite submarine cable connecting floating structures and underwater devices to address the problem of metal armor failure under its own gravity, circumferential compression from high water pressure, and repeated environmental loads. The existing submarine cable is mainly applied in water depths within 1000 meters, with very few practical applications beyond 1,000 meters.

When the existing submarine cable is deployed in an ultra-deepwater area, the following problems will arise:

1. (1) during the process of laying the submarine cable into deep water, the seawater enters the interior of the submarine cable from one end of the submarine cable. Due to the certain speed of laying, the air inside of the submarine cable cannot be discharged in time, and these air will form a huge air pressure after being accumulated, leading to bulging or even rupture of the sheath;
2. (2) as the water depth increases, the radial pressure of the seawater on the submarine cable increases. There is air inside the submarine cable, so that a great pressure difference exists inside and outside the submarine cable, and the high pressure formed by the seawater outside the submarine cable easily cause the submarine cable to collapse and fail;
3. (3) when the submarine cable is operated in the ultra-deepwater area, the filling strips inside the submarine cable are in a sealed state, and the filling strips are easy to be flattened and broken under the extrusion of the external seawater. The cable cores are also subjected to the high pressure, which can cause insulation shrinkage and damage. At the same time, the seawater will penetrate into the phase-separating sheath, causing corrosion of the metal shielding layer;
4. (4) the armor layer of the submarine cable needs to withstand a great tension force when being laid into deep water, and when the strength of the armor layer is insufficient, a yielding failure will occur, affecting the normal operation of the submarine cable.

The present application provides an ultra-deepwater submarine cable, which aims to solve the defects in the prior art that when the submarine cable is applied to an ultra-deepwater area, a pressure difference exists inside and outside the submarine cable because there is air inside the submarine cable, leading to the submarine cable being easily collapse and fail, and the filling strips and the cable cores being easily flattened and damaged.

The present application provides an ultra-deepwater submarine cable, including: a plurality of cable cores, a plurality of pre-formed filling strips and an outer protective structure, where the plurality of cable cores are tightly twisted together, the plurality of pre-formed filling strips are provided in gaps among the plurality of cable cores, and the outer protective structure is wrapped around outer peripheries of the plurality of cable cores and the plurality of pre-formed filling strips.

The pre-formed filling strip is provided with a cavity extending along a length direction thereof and through-holes provided at intervals along the length direction thereof, where the through-holes penetrate into the cavity radially, and the outer protective structure is provided with circulation holes provided at intervals along a length direction thereof, the gaps among the cable cores and the cavities of the pre-formed filling strips are communicated to exterior of the outer protective structure through the circulation holes.

When the ultra-deepwater submarine cable is laid on the seawater, the seawater can enter the gaps among the plurality of cable cores and the cavities of the pre-formed filling strips through the circulation holes on the outer protective structure, so that the air inside the submarine cable can be discharged smoothly, thereby avoiding the accumulation of air pressure which will cause the structure bulge and damage, and ensuring the normal laying of the submarine cable. In addition, the cavities of the pre-formed filling strips are filled with seawater, so that an internal pressure and an external pressure of the submarine cable are balanced and an internal structure of the submarine cable will not be flattened, thereby ensuring the normal transmission of electricity and prolonging the service life of the submarine cable at the same time.

According to an ultra-deepwater submarine cable provided in the present application, the number of the cable cores is three, and the number of the pre-formed filling strips is three, where the three cable cores are tightly fitted to each other along a circumferential direction of the ultra-deepwater submarine cable, the three pre-formed filling strips are sequentially filled between two adjacent cable cores at intervals, and the three pre-formed filling strips and the three cable cores jointly form a substantially cylindrical structure.

An inner wall of the pre-formed filling strip can be fitted to the cable core, so as to achieve the effects of positioning and supporting the cable core. In addition, the three pre-formed filling strips and the three cable cores jointly form a substantially cylindrical structure, thereby facilitating the outer protective structure to be sheathed outside.

According to an ultra-deepwater submarine cable provided in the present application, the pre-shaped filling strip includes a first arc portion, a second arc portion and an outer arc portion which are connected end to end in sequence, where the first arc portion and the second arc portion are respectively used to be fitted to the two adjacent cable cores, the cavity is provided inside the first arc portion, the second arc portion and the outer arc portion, the through-hole is provided on the outer arc portion, and the circulation hole of the outer protective structure is communicated with the cavity through the through-hole of the outer arc portion.

The cross-sections of the first arc portion and the second arc portion are substantially configured to be arc-shaped, and the first arc portion and the second arc portion can be adaptively fitted to outer walls of the two adjacent cable cores, respectively. The cross-section of the outer arc portion is also substantially configured to be arc-shaped, and the respective outer arc portions of the three pre-shaped filling strips can jointly form a substantially cylindrical outer wall structure, so as to facilitate the outer protective structure being provided outside the three pre-formed filling strips.

According to an ultra-deepwater submarine cable provided in the present application, a first reinforcing rib is provided between the first arc portion and the outer arc portion, a second reinforcing rib is provided between the second arc portion and the outer arc portion, and the first reinforcing rib and the second reinforcing rib divide the cavity into three isolation cavities, and the through-holes on the outer arc portion are respectively provided corresponding to each of the isolation cavities.

The first reinforcing rib and the second reinforcing rib may extend in a radial direction of the submarine cable respectively, the first reinforcing rib and the second reinforcing rib are provided at intervals in a circumferential direction of the submarine cable, and the cavity inside the pre-shaped filling strip is sequentially divided into three isolation cavities through the first reinforcing rib and the second reinforcing rib. In this way, the pre-shaped filling strip is prevented from being compressed and deformed under the action of an external force of the seawater.

According to an ultra-deepwater submarine cable provided in the present application, the cable core includes: a waterproof conductor, and a conductor shielding layer, a cross-linked polyethylene insulation layer, an insulation shielding layer, an inner semi-conductive waterproof tape wrapping layer, a metal shielding layer, an outer semi-conductive waterproof tape wrapping layer, an aluminum-plastic composite tape layer, and a phase-separating sheath which are sequentially provided at an outer periphery of the waterproof conductor.

The outer periphery of the waterproof conductor may be extruded with the conductor shielding layer, an outer periphery of the conductor shielding layer may be provided with the cross-linked polyethylene insulation layer, an outer periphery of the cross-linked polyethylene insulation layer may be provided with the insulation shielding layer, an outer periphery of the insulation shielding layer may be wrapped with the inner semi-conductive waterproof tape wrapping layer, an outer periphery of the inner semi-conductive waterproof tape wrapping layer may be wrapped with the metal shielding layer, an outer periphery of the metal shielding layer may be wrapped with the outer semi-conductive waterproof tape wrapping layer, an outer periphery of the outer semi-conductive waterproof tape wrapping layer can be longitudinally wrapped with aluminum-plastic composite tape layer, and finally, the phase-separating sheath may be extruded and fitted to an outer periphery of the aluminum-plastic composite tape layer, so as to achieve the protective effect for the cable core.

According to an ultra-deepwater submarine cable provided in the present application, the outer periphery of the cable cores and the pre-formed filling strips are jointly provided with a cable-forming wrapping tape.

The pre-formed filling strips are provided in the cable-forming gaps among the three cable cores, and during forming the cable, the three cable cores and the pre-formed filling strips can be tightened by using the cable-forming wrapping tape, so as to ensure the roundness of the entire structure after the cable is formed.

According to an ultra-deepwater submarine cable provided in the present application, the outer protective structure includes an inner sheath, a first armor layer, a first armor wrapping tape, a second armor layer, a second armor wrapping tape and an outer sheath which are sequentially provided on the outer periphery of the cable cores and the pre-formed filling strips.

The inner sheath may be extruded on an outer periphery of the cable-forming wrapping tape, the first armor layer may be provided on an outer periphery of the inner sheath, the first armor wrapping tape may be provided on an outer periphery of the first armor layer, the second armor layer may be provided on an outer periphery of the first armor wrapping tape, the second armor wrapping tape may be provided on an outer periphery of the second armor layer, and finally, the outer sheath is extruded on an outer periphery of the second armor wrapping tape, so as to further achieve the new protective effect for the cable.

According to an ultra-deepwater submarine cable provided in the present application, the circulation hole of the outer protective structure includes a first through-hole provided on the inner sheath and a second through-hole provided on the outer sheath.

In this way, the cavities in the pre-formed filling strips may be communicated with the exterior of the outer protective structure through the first through-hole on the inner sheath and the second through-hole on the outer sheath, so that the external seawater can enter the cavities in the pre-formed filling strips through the second through-hole and the first through-hole.

According to an ultra-deepwater submarine cable provided in the present application, steel wires in the first armor layer and steel wires in the second armor layer have opposite twisting directions.

The outer protective structure adopts an armor structure with a plurality of layers of high-strength steel wires, and the plurality of layers of high-strength steel wires can jointly withstand a huge tension force when being mounted and laid, which can meet the usage requirements in large water depths. Meanwhile, the even-numbered layers of counter-twisted metal armor layers can meet the torque balance design requirements, and during the axial stretching process, each layer undergoes consistent deformation under stress, so that the tensile strength can be improved.

According to an ultra-deepwater submarine cable provided in the present application, the steel wires in the first armor layer and the steel wires in the second armor layer are designed with high-strength steel wires.

In this way, the first armor layer and the second armor layer jointly withstand a tension force applied during the installation of the submarine cable, and also have good corrosion resistance.

In conjunction with the described technical solutions, in the ultra-deepwater submarine cable provided in the present application, the outer protective structure is provided on the peripheries of the plurality of cable cores and the plurality of pre-formed filling strips, the pre-formed filling strip is provided with a cavity and through-holes provided at intervals along the length direction thereof and radially penetrating the cavity, the outer protective structure is provided with the circulation holes, so that when the ultra-deepwater submarine cable is laid and put into the deep sea, the seawater can enter the gaps among the plurality of cable cores and the cavities of the pre-formed filling strips through the circulation holes, and the air inside the submarine cable can be completely discharged, so as to maintain the pressure balance inside and outside the submarine cable and prevent the internal structure of the submarine cable from being crushed, thereby prolonging the service life of the submarine cable. Furthermore, the entire ultra-deepwater submarine cable is designed to have a light structure, which can reduce the overall outer diameter and self-weight, as well as material consumption and cost, and thus have certain economic benefits.

To describe the technical solutions in the present application or in the prior art more clearly, the accompanying drawings required in the embodiments or in the prior art will be briefly described below. Obviously, the accompanying drawings described below are merely some embodiments of the present application, and for those skilled in the art, other accompanying drawings can also be obtained based on these accompanying drawings without creative efforts.

• FIG. 1 is a structural schematic diagram of an ultra-deepwater submarine cable according to an implementation of the present application.
• FIG. 2 is a structural schematic diagram of a pre-formed filling strip in the ultra-deepwater submarine cable of FIG. 1.
• FIG. 3 is a three-dimensional structural schematic diagram of a pre-formed filling strip in the ultra-deepwater submarine cable in FIG. 1.
• FIG. 4 is a structural schematic diagram of an inner sheath of the ultra-deepwater submarine cable in FIG. 1.
• FIG. 5 is a structural schematic diagram of an outer sheath of the ultra-deepwater submarine cable in FIG. 1.

Reference numerals:
10, cable core; 11, waterproof conductor; 12, conductor shielding layer; 13, cross-linked polyethylene insulation layer; 14, insulation shielding layer; 15, inner semi-conductive waterproof tape wrapping layer; 16, a metal shielding layer; 17, an outer semi-conductive waterproof tape wrapping layer; 18, aluminum-plastic composite tape layer; 19, phase-separating sheath; 20, pre-formed filling strip; 21, first arc portion; 22, second arc portion; 23, outer arc portion; 24, through-hole; 25, first reinforcing rib; 26, second reinforcing rib; 27, first isolation cavity; 28, second isolation cavity; 29, third isolation cavity; 30, outer protective structure; 31, inner sheath; 32, first armor layer; 33, first armor wrapping tape; 34, second armor layer; 35, second armor wrapping tape; 36, outer sheath; 37, first through-hole; 38, second through-hole; 40, cable-forming wrapping tape.

To make the purposes, technical solutions, and advantages of the present application clearer, the technical solutions in this application will be described clearly and completely below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

It can be known by those skilled in the art that the ocean accounts for about 71% of the earth's surface and stores abundant energy resources such as oil and gas, natural gas hydrates and solid minerals, which serves as an important energy security base and strategic operational space for human beings. The abundant oil and mineral resources are usually located several kilometers underwater. The sea area with depth exceeding 6500 meters in the sea is referred to as the abyss, and the abyss area is one of the last unexploited areas by humans on the earth.

In order to achieve underwater exploration and energy resources exploitation, an underwater drilling and mining device needs to be used. When the underwater drilling and mining device is used, it is necessary to transport electrical energy from an oil and gas platform to the underwater drilling and mining device through a submarine cable with a length suitable for the water depth. The submarine cable in the deep sea may withstand high water-depth squeezing effect, which can easily cause structural deformation and failure accidents.

In order to meet the requirements for mining in ultra-deepwater areas, according to an embodiment of the present application, an ultra-deepwater submarine cable is provided, which can be used to transport electric energy for the underwater drilling and mining device.

The ultra-deepwater submarine cable includes a plurality of cable cores, a plurality of pre-formed filling strips, and an outer protective structure, where the pre-formed filling strip is provided with a cavity and through-holes, the outer protective structure is provided with circulation holes, and when the ultra-deepwater submarine cable is put into the deep sea, the seawater can enter the cavities of the pre-formed filling strips through the circulation holes, so that the pressure balance is maintained inside and outside the submarine cable, and an internal structure of the submarine cable is prevented from being crushed, thereby prolonging the service life of the submarine cable. The ultra-deepwater submarine cable in this embodiment is further described below with reference to FIG. 1-FIG. 5.

As shown in FIG. 1, the ultra-deepwater submarine cable in this embodiment includes: a plurality of cable cores 10, a plurality of pre-formed filling strips 20, and an outer protective structure 30.

The plurality of cable cores 10 are tightly twisted together, the plurality of pre-formed filling strips 20 are provided in gaps among the plurality of cable cores 10, and the outer protective structure 30 is wrapped around the outer peripheries of the plurality of cable cores 10 and the plurality of pre-formed filling strips 20.

Exemplarily, as shown in FIG. 1, the cable core 10 is configured in a long strip shape, an energized conductor is provided inside the cable core and can be used for transmitting electric energy, and the plurality of cable cores 10 are tightly twisted and mounted at a central position of the ultra-deepwater submarine cable. The pre-formed filling strips 20 are provided to be tightly fitted to the cable cores 10, and may be filled in gaps among the cable cores 10, thereby achieving the effects of positioning and supporting the cable cores 10.

The outer protective structure 30 is substantially configured as an elongated cylindrical structure, and the cable cores 10 and the pre-formed filling strips 20 are all provided inside the outer protective structure 30. After the ultra-deepwater submarine cable is placed into the deep sea, the outer protective structure 30 can directly contact the seawater, and can protect the cable cores 10.

In this embodiment, the pre-formed filling strip 20 is provided with a cavity extending along a length direction thereof and through-holes 24 provided at intervals along the length direction thereof, where the through-holes 24 penetrate into the cavity radially, the outer protective structure 30 is provided with circulation holes provided at intervals along a length direction thereof, and the cavities of the pre-formed filling strips 20 is communicated to exterior of the outer protective structure 30 through the circulation holes.

It can be understood that the pre-shaped filling strip 20 is in a hollow structure, the cavity in the pre-shaped filling strip 20 extends along a length direction of the ultra-deepwater submarine cable, and the cavities of the pre-shaped filling strips 20 may be communicated with the outside through the through-holes 24 and the circulation holes on the outer protective structure 30.

Furthermore, since the ultra-deepwater submarine cable has a certain length, when the ultra-deepwater submarine cable is laid into seawater, it is necessary to ensure that the seawater can enter the cavity of the pre-formed filling strip 20 in time. In this regard, in this embodiment, the through-holes 24 are provided at intervals along the length direction of the pre-formed filling strip 20, and the circulation holes are provided at intervals along the length direction of the outer protective structure 30.

When the ultra-deepwater submarine cable in this embodiment is laid into seawater, the seawater can enter the gaps among the plurality of cable cores and the cavities of the pre-formed filling strips 20 through the circulation holes on the outer protective structure 30, so that the air inside the submarine cable can be discharged smoothly, thereby avoiding the accumulation of air pressure which will cause the structure bulge and damage, and ensuring the normal laying of the submarine cable.

When the ultra-deepwater submarine cable in this embodiment is laid into seawater, the cavities of the pre-formed filling strips 20 are filled with the seawater, so that an internal pressure and an external pressure of the submarine cable are balanced, and the internal structure of the submarine cable is not flattened, thereby ensuring the normal transmission of electricity and prolonging the service life of the submarine cable at the same time.

In this embodiment, as shown in FIG. 1, the number of the cable cores 10 is three, the number of the pre-formed filling strips 20 is three, where the three cable cores 10 are tightly fitted to each other along a circumferential direction of the ultra-deepwater submarine cable, the three pre-formed filling strips 20 are sequentially filled between two adjacent cable cores 10 at intervals, and the three pre-formed filling strips 20 and the three cable cores 10 jointly form a substantially cylindrical structure.

Specifically, the three cable cores 10 may be tightly fitted to each other around a central axis of the submarine cable, each cable core 10 is generally in a long cylindrical structure, and a gap exists between the outer periphery of two adjacent cable cores 10, and the three pre-formed filling strips 20 are provided in the three gaps in one-to-one correspondence. Furthermore, an inner wall of the pre-shaped filling strip 20 may be closely attached to the cable core 10, so as to achieve the effects of positioning and supporting the cable core. Meanwhile, an outer wall of the pre-shaped filling strip 20 may be substantially configured to be arc-shaped, and at this time, the three pre-shaped filling strips 20 and the three cable cores 10 jointly form a substantially cylindrical structure, thereby facilitating the outer protective structure 30 to be sheathed outside.

In a specific embodiment, as shown in FIG. 2, the pre-shaped filling strip 20 includes a first arc portion 21, a second arc portion 22 and an outer arc portion 23 which are connected end to end in sequence, where the first arc portion 21 and the second arc portion 22 are respectively used to be fitted to the two adjacent cable cores 10, and the cavity is formed inside the first arc portion 21, the second arc portion 22 and the outer arc portion 23 connected end to end, the through-holes 24 are provided on the outer arc portion 23, and the circulation holes of the outer protective structure 30 are communicated with the cavity through the through-holes 24 of the outer arc portion 23.

It can be understood that the cross-sections of the first arc portion 21 and the second arc portion 22 are substantially configured to be arc-shaped, and the first arc portion 21 and the second arc portion 22 can be adaptively fitted to the outer walls of two adjacent cable cores 10, respectively. The cross-section of the outer arc portion 23 is also substantially configured to be arc-shaped, and the respective outer arc portions 23 of the three pre-shaped filling strips 20 can jointly form a substantially cylindrical outer wall structure, so as to facilitate the outer protective structure 30 being provided outside the three pre-formed filling strips 20.

Furthermore, in order to prevent the pre-formed strip 20 from being compressed and deformed under the external force of the seawater, as shown in FIG. 2, a first reinforcing rib 25 is provided between the first arc portion 21 and the outer arc portion 23, a second reinforcing rib 26 is provided between the second arc portion 22 and the outer arc portion 23,where the first reinforcing rib 25 and the second reinforcing rib 26 divide the cavity into three isolation cavities, and the through-holes 24 on the outer arc portion 23 are respectively provided corresponding to each of the isolation cavities.

It can be understood that the first reinforcing rib 25 and the second reinforcing rib 26 may extend along a radial direction of the submarine cable respectively, the first reinforcing rib 25 and the second reinforcing rib 26 are provided at intervals in a circumferential direction of the submarine cable, and the cavity inside the pre-shaped filling strip 20 is sequentially divided into three isolation cavities through the first reinforcing rib 25 and the second reinforcing rib 26.

For example, as shown in FIG 2, the cavity inside the pre-formed filling strip 20 is divided into a first isolation cavity 27, a second isolation cavity 28, and a third isolation cavity 29.

Accordingly, in order to enable the three isolation cavities to be communicated with the outside, as shown in FIG. 2 and FIG. 3, the through-holes 24 on the outer arc portion 23 are respectively provided corresponding to each of the isolation cavities. At this time, each outer arc portion 23 is provided with three through-holes 24 in sequence along the circumferential direction of the submarine cable.

Of course, in other embodiments, other numbers of ribs can also be provided according to the analysis of the water pressure effect at different water depths, so as to ensure that the pre-formed filling strip will not collapse in practical applications.

In this embodiment, as shown in FIG. 1, the cable core 10 includes: a waterproof conductor 11, and a conductor shielding layer 12, a cross-linked polyethylene insulation layer 13, an insulation shielding layer 14, an inner semi-conductive waterproof tape wrapping layer 15, a metal shielding layer 16, an outer semi-conductive waterproof tape wrapping layer 17, an aluminum-plastic composite tape layer 18, and a phase-separating sheath 19 which are sequentially provided at an outer periphery of the waterproof conductor 11.

As an implementation, the outer periphery of the waterproof conductor 11 may be extruded with the conductor shielding layer 12, an outer periphery of the conductor shielding layer 12 may be provided with the cross-linked polyethylene insulation layer 13, an outer periphery of the cross-linked polyethylene insulation layer 13 may be provided with the insulation shielding layer 14, an outer periphery of the insulation shielding layer 14 may be wrapped with the inner semi-conductive waterproof tape wrapping layer 15, an outer periphery of the inner semi-conductive waterproof tape wrapping layer 15 may be wrapped with the metal shielding layer 16, an outer periphery of the metal shielding layer 16 may be wrapped with the outer semi-conductive waterproof tape wrapping layer 17, an outer periphery of the outer semi-conductive waterproof tape wrapping layer 17 can be longitudinally wrapped with aluminum-plastic composite tape layer 18, and finally, the phase-separating sheath 19 may be extruded and fitted to an outer periphery of the aluminum-plastic composite tape layer 18.

In this embodiment, the structures of the three cable cores 10 are the same, and at this time, there are three waterproof conductors 11 in the ultra-deepwater submarine cable.

Exemplarily, copper or aluminum is adopted as a material of the waterproof conductor 11, and when the waterproof conductor 11 is twisted, it can be filled with semi-conductive waterproof adhesive. The waterproof adhesive has extremely strong waterproof performance, and can effectively prevent the seawater from permeating into the interior of the conductor, thereby meeting the usage requirements in large water depths. Meanwhile, the outermost layer of the waterproof conductor 11 may also be wrapped with two layers of semi-conductive waterproof tapes, so that a wire core of the waterproof conductor 11 has a longitudinal waterproof performance.

Optionally, a volume resistivity of the semi-conductive waterproof adhesive used in the waterproof conductor 11 is ≤ 1×105Ω•cm (23 ± 2°C), a thermal loss under the condition of 200°C for 2 hours is less than 2%, and a tensile elongation at break after the waterproof adhesive is cured is ≥ 600%, thereby ensuring the cohesiveness between the waterproof adhesive and the conductor when the conductor repeats bending.

Exemplarily, the conductor shielding layer 12 is made by extruding semi-conductive shielding material.

Exemplarily, the cross-linked polyethylene insulation layer 13 is made of water-tree resistant cross-linked polyethylene material, which is uniformly extruded on the outer periphery of the conductor shielding layer 12.

Optionally, the cross-linked polyethylene insulation layer 13 may be designed with the thinnest thickness that meets the field strength requirements.

Exemplarily, the insulation shielding layer 14 may be made of semi-conductive shielding material, which is directly extruded on the outer periphery of the cross-linked polyethylene insulation layer 13.

Exemplarily, both the inner semi-conductive waterproof tape wrapping layer 15 and the outer semi-conductive waterproof tape wrapping layer 17 may be made of a semi-conductive water-proof tape, which may be wrapped around the outer periphery of the insulation shielding layer 14 synchronously with the metal shielding layer 16.

Exemplarily, the metal shielding layer 16 can be made of two layers of copper strips with a thickness of 0.1 mm or 0.12 mm. In addition, the metal shielding layer 16 may be wrapped and constructed with single-layer overlapping or double-layer gap-overlapping winding method, and a width thereof may be selected according to an outer diameter of the cable core and the requirements for short-circuit current.

Exemplarily, the aluminum-plastic composite tape layer 18 can be longitudinally wrapped with a layer of aluminum-plastic composite tape with a thickness of 0.245mm, the longitudinal wrapping overlap is sealed by welding, and a width thereof may be calculated according to the outer diameter of the cable core and selected according to the process method.

Exemplarily, the phase-separating sheath 19 is made of semi-conductive polyethylene material, which is directly wrapped around the outer periphery of the aluminum-plastic composite tape layer 18, so as to protect the whole cable core 10, and also have a certain waterproof effect.

In the cable core 10, the cross-linked polyethylene insulation layer 13 is designed to have the thinnest thickness which meets the field strength requirements, and the metal shielding layer 16 is designed with the thinnest metal strip which meets the short-circuit current requirements. As a result, the outer diameter of the submarine cable can be reduced, the overall self-weight can also be reduced, and thereby reducing the tension force required for laying in the deep water and meeting the usage requirements in large water depths.

In addition, the outer periphery of the metal shielding layer 16 is covered with a layer of aluminum-plastic composite tape, which can achieve the effect of radially blocking water in the ultra-deepwater environment, and can effectively reduce the possibility of corrosion of the metal tape caused by the seawater penetrating from the phase-separating sheath into the metal shielding layer 16. Meanwhile, under a high water pressure, the pressure applied to the inner insulation wire core can be greatly reduced, thereby effectively preventing the insulation wire core from being crushed and damaged.

Furthermore, the pre-formed filling strip 20 may be formed by mixing and extruding plastics such as polyethylene and polyvinyl chloride with calcium carbonate, where the calcium carbonate is used for increasing the strength of the pre-formed filling strip.

In this embodiment, as shown in FIG. 1, the outer periphery of the cable core 10 and the pre-shaped filling strip 20 is jointly provided with a cable-forming wrapping tape 40.

It can be understood that, the pre-formed filling strips 20 are provided in cable-forming gaps of the three cable cores 10, and during the cable forming, the three cable cores 10 and the pre-formed filling strips 20 may be tightened by using the cable-forming wrapping tape 40.

Exemplarily, a layer of gummed cotton strip with a thickness of 0.3 mm is selected for the cable-forming wrapping tape 40, and the gummed cotton strip is used to tighten the three cable cores 10 and the pre-formed filling strips 20, so as to ensure the roundness of the entire structure after the cable is formed.

In this embodiment, as shown in FIG. 1, the outer protective structure 30 includes an inner sheath 31, a first armor layer 32, a first armor wrapping tape 33, a second armor layer 34, a second armor wrapping tape 35, and an outer sheath 36 which are sequentially provided on the outer periphery of the cable cores 10 and the pre-formed filling strips 20.

As an implementation, the inner sheath 31 may be extruded on an outer periphery of the cable-forming wrapping tape 40, the first armor layer 32 may be provided on an outer periphery of the inner sheath 31, the first armor wrapping tape 33 may be provided on an outer periphery of the first armor layer 32, the second armor layer 34 may be provided on an outer periphery of the first armor wrapping tape 33, the second armor wrapping tape 35 may be provided on an outer periphery of the second armor layer 34, and finally, the outer sheath 36 is extruded on an outer periphery of the second armor wrapping tape 35.

For example, the inner sheath 31 can be made of high-density polyethylene material, which is extruded directly onto the cable-forming wrapping tape 40.

Exemplarily, the first armor layer 32 can be made of a layer of high-strength zinc-plated steel wires, which is used to withstand the tension force applied during the installation of the submarine cable, and also has good corrosion resistance.

Similarly, the second armor layer 34 may also be made of a layer of high-strength zinc-plated steel wires, and may withstand the tension force applied together with the first armor layer 32 during the installation of the submarine cable, and also has good corrosion resistance.

It can be understood that the steel wires after the galvanizing treatment have better corrosion resistance, which can effectively prevent the seawater corrosion and meet the usage requirements in large water depths.

Meanwhile, the steel wires in the first armor layer 32 and the steel wires in the second armor layer 34 may have opposite twisting directions, for example, a twisting direction of the steel wires in the first armor layer 32 is to the right, while a twisting direction of the steel wires in the second armor layer 34 is to the left, so as to balance the torque.

It can be understood that the outer protective structure adopts an armor structure with a plurality of layers of high-strength steel wires, and the plurality of layers of high-strength steel wires can jointly withstand a huge tension force during installation and laying, which can meet the usage requirements in large water depths. Meanwhile, the even-numbered layers of counter-twisted metal armor layers can meet the design requirement of torque balance can meet the torque balance design requirements, and during the axial stretching process, each layer undergoes consistent deformation under stress, so that the tensile strength can be improved.

Exemplarily, a layer of gummed cotton cloth tape with a thickness of 0.3 mm is selected for the first armor belt 33, which is used to tighten the steel wires in the first armor layer 32, so as to ensure the roundness of the structure after the first layer is armored.

Similarly, two layers of PBT wrapping tape with a thickness of 0.5 mm are selected for the second armor wrapping tape 35, which is used to tighten the steel wires in the second armor layer 34 and all internal structures therein, and so as to ensure the roundness of the structure after the second layer is armored.

For example, the outer sheath 36 may be made of high-density polyethylene material, which is extruded directly around the outer periphery of the second wrapping tape 35.

The outer sheath 36 is used as a structure in direct contact with the outside, an outer surface of the outer sheath 36 may be provided with a marker in order to facilitate recognition. For example, the color of the outer surface of the outer sheath 36 can be designed into a yellow main body with narrow black strips. The yellow main body facilitates finding the position of the submarine cable in deep water, and the narrow black strips can monitor the twisting angle during the extension of the submarine cable.

In this embodiment, as shown in FIG. 4 and FIG. 5, the circulation hole of the outer protective structure 30 includes a first through-hole 37 provided on the inner sheath 31 and a second through-hole 38 provided on the outer sheath 36.

That is to say, the cavities in the pre-formed filling strips 20 may be communicated with the outside of the outer protective structure 30 through the first through-hole 37 on the inner sheath 31 and the second through-hole 38 on the outer sheath 36, so that the external seawater can enter the cavities in the pre-formed filling strips 20 through the second through-hole 38 and the first through-hole 37.

Exemplarily, the first through-hole 37 on the inner sheath 31 may be sequentially provided at intervals along a length direction of the inner sheath 31, a distance between two adjacent first through-holes 37 can be determined according to a laying speed of the submarine cable and water pressure analysis, and an opening size of the first through-hole 37 can be determined according to a free overflow rate and water pressure analysis.

Similarly, the second through-holes 38 on the outer sheath 36 may be sequentially provided at intervals along a length direction of the outer sheath 36, a distance between two adjacent second through-holes 38 may be determined according to the laying speed of the submarine cable and the water pressure analysis, and an opening size of the second through-hole 38 is determined according to the free overflow rate and the water pressure analysis.

In addition, a thickness of the outer sheath 36 may be determined according to water pressure requirements, so as to ensure that the outer sheath 36 has better protection effect and mechanical properties such as wear and pressure resistance.

It can be seen that the ultra-deepwater submarine cable in this embodiment includes: a plurality of cable cores, a plurality of pre-formed filling strips and an outer protective structure, where the outer protective structure is provided on the outer periphery of the plurality of cable cores and the plurality of pre-formed filling strips, each pre-formed filling strip is provided with a cavity and through-holes provided at intervals along a length direction thereof and radially penetrating the cavity, the outer protective structure is provided with the circulation holes, so that when the ultra-deepwater submarine cable is laid and put into the deep sea, the seawater can enter the gaps among the plurality of cable cores and the cavities of the pre-formed filling strips through the circulation holes, and the air inside the submarine cable can be completely discharged, so as to maintain the pressure balance inside and outside the submarine cable and prevent the internal structure of the submarine cable from being crushed, thereby prolonging the service life of the submarine cable.

Furthermore, the entire ultra-deepwater submarine cable is designed to have a light structure, which can reduce the overall outer diameter and self-weight, as well as material consumption and cost, and thus have certain economic benefits.

The device embodiments described above are merely exemplary, where the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. A part or all of the modules may be selected according to actual needs to achieve the objectives of the solutions in the embodiments. Those skilled in the art would have been able to understand and implement same without involving any creative effort.

Finally, it should be noted that the above embodiments are merely used to illustrate the technical solutions of the present application rather than limiting the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those ordinary skilled in the art should understand that they may still make modifications to the technical solutions described in the above-mentioned embodiments, or make equivalent replacements to some technical features thereof. These modifications or replacements do not make the essence of the corresponding technical solutions depart from the spirit and the scope of the technical solutions in the embodiments of the present application.