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How Many Different Methods To Install Fiber Optical Cable?

Views: 0     Author: Curry     Publish Time: 2024-09-26      Origin: www.fcst.com

Due to different construction conditions and construction requirements, fiber optical cables will be laid in different methods and scenarios. Most regular laying methods includes: direct burial, overhead(aerial installation), pipeline (underground), underwater and Indoor, etc.


1. Direct Burial


Direct burial refers to the laying method of burying optical cables directly in the underground soil. Usually, in ordinary soil and hard soil, optical cables need to be buried below 1.2 meters from the surface.


During the construction of directly buried optical cables, it is necessary to dig the ground base on the request, then lay the buried optical cable to the bottom of the trench,  and then backfill the soil. In order to make it easier to find the laying location of the optical cable during maintenance, after filling back the soil, marking stones will be buried on the surface every 50 meters. Directly buried optical cables can be laid manually or mechanically.Direct Burial Fiber Cable

                                                                                 Figure 1 shows the construction of direct buried optical cables


Directly buried optical cables generally use GYTA53 structure. This structure is equivalent to adding a chrome-plated steel strip and a polyethylene outer sheath to the sheath of ordinary GYTA optical cables, as shown in Figure 2, so that the optical cable has better protective performance.

Fiber Optic Cable

                                                                Figure 2 is a schematic diagram of the GYTA53 optical cable structure.


In the 1990s, large-scale construction of long-distance optical cable lines (including the current first trunk line and second trunk line) began across the country. At that time, long-distance optical cable lines mainly used direct burial. The safety of directly buried optical cable lines is better, but the construction and maintenance costs are high and it is difficult to expand the capacity. Therefore, it is gradually replaced by long-distance plastic pipe air blowing and other laying methods. Currently, it is used in some sections where the land is sparsely populated and the overhead laying method is not suitable ( Such as: grassland, desert) there is still a small amount of construction.

From the perspective of project management, the construction content of long-distance plastic pipes buried in the wild is similar to that of direct-buried optical cables. Therefore, some owners often manage air-blown optical cables buried in long-distance plastic pipes in the wild as direct-buried optical cable line projects, but from the perspective of the optical cable laying method The above should belong to the laying of pipeline optical cables.


2. Overhead(aerial installation)


The overhead of optical cable means that the optical cable relies on supports such as poles to suspend the optical cable in a space of 3.0 meters to 8.0 meters above the ground. The supports used for overhead optical cables are mainly electric poles, and the pole spacing (the distance between adjacent electric poles) is generally about 50 meters.

                      

Aerial Fiber Cable

                                                                                                          Figure 3 Aerial optical cable line


Aerial fiber optic cables are cheaper to build, but are also less secure. It is often easy to get hung up by over-height vehicles when crossing roads; when floods occur, connected pole roads often get washed away.

Aerial Fiber Cable-1

                                                                                            Figure 4 The washed-out overhead optical cable line


3. Pipeline Laying


Pipeline laying of optical cables usually refers to laying optical cables in underground communication pipes through traction or air blowing. Underground communication pipelines generally consist of a pipe group buried under the surface and manholes (handhole) at both ends of the pipe group. A tube cluster usually consists of one or more plastic tubes. Depending on the construction area and section length, underground communication pipelines are usually divided into urban pipelines and long-distance pipelines.

Indoor pipelines are usually built in areas with dense communication services such as urban areas, suburbs or market towns, and the section length is about 100 meters. Optical cables are generally laid in pipelines through manhole traction or mechanical traction.

Long-distance pipelines are usually constructed in the wild. The pipes are made of 40mm/33mm silicon core plastic pipes, with a section length of about 980 meters. Optical cables need to be laid in the pipeline by air blowing, as shown in Figure 5. Air blowing cable laying is to blow compressed air into the silicon core tube, so that the penetrated optical cable becomes suspended in the silicon core tube along with the high-speed air flow. At the same time, the crawler conveyor mechanism of the cable blowing machine clamps the optical cable and transports it forward.

Fiber Blowing Machines

                                                                                                                   Figure 5 Fiber Cable Blowing


In order to improve the utilization rate of pipe hole resources, microduct and Micro cable have been widely used in telecommunication pipelines along highways.


4. Optical cable laying in high-speed railway tunnel


Laying optical cables along high-speed rail lines is not only easy to construct and highly secure, but communication trunk lines can also shorten relay distances and reduce transmission delays. In recent years, it has become increasingly common for trunk optical cables to be constructed along high-speed rail lines.

High-speed rail lines themselves have power and communication needs. Strong-current and weak-current channels are set up on both sides of the rails. Communication optical cables are laid in weak-current channels, as shown in Figure 6.

The type of optical cable laid through the weak current channel of high-speed rail usually uses GYTA58. This type of optical cable has the same structure as the GYTA53 optical cable, but the outer coating of the optical cable is made of low-smoke, halogen-free, flame-retardant polyethylene (the outer coating of the GYTA53 optical cable is

polyethylene), so the optical cable has certain flame-retardant properties.

Optical cable laying in high-speed railway tunnel

                                                                                     Figure 6 Optical cable laying in high-speed railway tunnel


In addition to the four common laying methods of direct burial, pipelines, and overhead, with the construction of high-speed rail lines in recent years, there are more and more scenarios where optical cables are laid along high-speed rail channels. In addition, direct-buried lines (direct-buried optical cables and directly-buried silicon core pipes) involve underwater laying when crossing rivers. When optical cables enter the office station, they need to be laid in the office station.


References

【1】GB 51158-2015 Communication line engineering design specifications

【2】GB 51171-2016 Communication line engineering acceptance specifications


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