I. Excavation of Direct-Buried Cable Trenches for Cable Projects

　　Cable Engineering Process Standards:

　　(1) Investigate the pipeline and obstacle conditions in the cable-crossing areas of the cable project, and excavate sample trenches at appropriate locations. The excavation depth shall exceed the burial depth of the cable.

　　(2) Trench excavation for cable routes in cable engineering shall comply with the following requirements:

　　1) The clearance between the ground and the cable sheath shall be no less than 0.7 m; for cables of 35 kV and above, the clearance shall be no less than 1 m. 2) When crossing roads and farmland, the clearances shall be 1 m and 1.2 m, respectively. 3) When crossing urban traffic roads and railway tracks, the installation shall comply with the requirements of the design specifications, and protective measures shall be implemented. 4) During construction in cold regions, the excavation depth shall also meet the requirement that the cable be laid below the frost line, or special measures such as conduit protection shall be adopted.

　　Key construction points for cable engineering:

　　(1) Excavation of trenches shall be preceded by the installation of shoring. (2) In accordance with the approved design documents, a sufficient number of trial pits shall be excavated prior to cable laying to ascertain the subsurface utility locations and soil conditions along the route, thereby determining the correct cable alignment. (3) The depth of the trial pits shall exceed the intended burial depth of the cables. (4) During pavement excavation, pavement materials and excavated soil shall be stockpiled separately, with a clear access passage of at least 300 mm maintained between the stockpile areas and the trench edges. The height of the stockpiles shall not exceed 0.7 m. (5) Dust-control measures shall be implemented during earthwork operations. (6) Directly buried cables in slope areas shall be laid in a serpentine pattern with a curve radius of 1.5 m to reduce the cable-laying gradient, minimize tensile forces at high points, and enhance resistance to scouring by floodwaters.

　　II. Direct Burial Cable Laying in Cable Engineering

　　Process Standard:

　　(1) For cables directly buried underground, a layer of soft soil or sand at least 100 mm thick shall be laid, followed by two layers of cable protection boards. Where necessary, precast reinforced concrete slabs shall be used to protect the two layers of protection boards. The coverage width on each side of the cable shall exceed 50 mm, after which the cable shall be protected with precast reinforced concrete slabs. (2) When cables cross urban traffic roads and railway tracks, protective measures shall be implemented. (3) Cables shall be neatly arranged and uniformly bent. When cables are laid along the same route, they shall not cross at bends. (4) During installation, cables shall be free from mechanical damage. For direct-buried cable junction boxes (except epoxy resin junction boxes), an external protective box shall be provided to prevent mechanical damage.

　　Key construction points for cable engineering:

　　(1) Prior to cable laying, a cable payout rack shall be installed at the cable reel and at all bends; the cable reel, pulling machine, and compactor shall be positioned appropriately. The cable reel shall be equipped with a braking device. (2) Cables shall be fitted with a pulling head. When setting up the laying equipment, anti-torsion devices shall be installed between the pulling head or wire mesh sleeve and the pulling steel wire rope. The pulling force shall comply with the requirements of the acceptance specifications. Protective measures shall be implemented at cable pulling heads, cable reels, towing vehicles, intersections, bends, and any other locations where the cable may be damaged. A dedicated person shall be assigned to monitor the operation and ensure smooth communication. (3) After cable laying but before backfilling, survey personnel shall be notified to survey the laid cables. (4) The clearances between cables and other pipelines, roads, buildings, and other structures where parallel crossings occur shall comply with design requirements or relevant regulations. It is strictly prohibited to lay cables in parallel above or below pipelines. (5) Cables shall be laid in straight runs with minimal overlap, and accumulation of water and damp sections should be avoided as much as possible.