The implementation of the direct-buried optical cable project should be carried out according to the engineering design commission or the communication network planning plan. The construction mainly includes the route digging and filling of the optical cable trench, the plan design, and the setting of markers.
1. Digging and filling optical cable trench
(1) The depth of trenching. Directly buried optical cables need to dig trenches to fill the optical cables, so the depth of the trenches needs to be considered. For different soil types, different depths need to be excavated. In actual construction, the trenching specifications must be strictly followed.
(2) Width of trenching. If you need to lay two optical cables in the trench, the width of the trench bottom should be greater than 0.3m to ensure that there is a distance of more than 0.1m between the two lines.
(3) Backfill the optical cable trench. After laying the optical cable, backfill the earth. Generally speaking, loose filling is sufficient for sparsely populated areas such as fields and hillsides. In other cases, ram filling is required to ensure line safety.
(4), junction box protection. The optical cables are connected by a junction box. The junction box is the core component of the optical cable. Special protection is required. Usually, 4 cement tiles are placed on the top to protect the junction box when backfilling.
2. Route selection scheme design
All kinds of influences should be fully considered in the selection of optical cable line routing scheme. Always take communication quality and line safety as the prerequisite. Therefore, the following points should be paid attention to for directly buried optical cables.
(1) Geological selection. The appropriate choice of fiber optic cable lines should avoid areas with frequent natural disasters, and should not be installed in places with harsh geological conditions as much as possible. Severe geological conditions include landslides, mud-rock flows, goafs, settlement areas, etc. In addition, there are also places where the physical and chemical properties of sand, saline soil, etc. are unstable, which can largely damage optical cables. The more suitable filling places are those places where the terrain changes gently and the amount of earthwork is small.
(2) Wading options. Optical cable lines should be detoured reasonably through lakes, swamps, reservoirs, ponds, river ditches and other drainage and flood storage areas. For example, when the optical cable line passes through the reservoir, the optical cable should be laid upstream of the reservoir and above the highest water level. When the fiber optic cable line needs to cross the river, it is necessary to choose the bridge as the erection medium as much as possible to reduce the construction of the underwater cable.
(3) City selection. When selecting direct-buried optical cable routing, keep the distance from other building facilities and comply with the minimum clear distance construction specifications. Generally speaking, optical cables should not pass through industrial land such as large factories and mining areas. When necessary, protective measures should be considered. In addition, fiber optic cable lines should try to avoid areas with dense human activities such as towns and villages, and areas with above-ground structures. When it is necessary to pass through these areas, it is necessary to consider the local architectural development plan to protect the original landform and reduce damage.
3. Marking stone setting
(1) Types and applications of markers. After the directly buried optical cable is bought underground, it needs to have corresponding markers on the ground to facilitate subsequent maintenance and management. For example, set joint markers at fiber optic cable connectors, turn markers at turning points, start and end points of streamline lines, set reserved markers at special reserved points, set intersection markers at crossing points with other cables, and cross obstacle locations Set obstacle markers and straight line markers.
(2) The number, height and label of the markers. Marking stones should be set up in accordance with the requirements of the state or provincial and municipal departments. Except for special mark stones, the average straight mark stone is given to one piece of 50m. The buried depth standard of special mark stones is 60cm. Unearthed 40cm, the allowable deviation is ±5cm. The surrounding area should be compacted, and the area of 60cm should be clean and tidy. The form of hidden mark can be used on urban roads. Marking stones should be located accurately, bury upright, complete and complete, have the same paint, write correctly, write clearly, and comply with the regulations of relevant regions and industries.