When the cable temperature is too high, the aging of the cable insulation will be aggravated, affecting the service life of the cable. The temperature rise of cables in different cable channels is also different. Therefore, it is necessary to carry out the influence law of cable tunnel shape on cable temperature rise characteristics, and study the relationship between cable number and arrangement mode and the maximum temperature of cable core, so as to provide a basis for selecting appropriate cable channel laying and cable group number distribution for newly put into the power grid.

   The selected cable tunnels are 1.5 m × 1.8 m single-track tunnel, 1.5 m × 1.8 m parallel tunnel, 2.0 m diameter pipe jacking, and 2.0 m diameter parallel pipe jacking. The cables are arranged in a triangle, and three cables are in a group. The cable tunnel is arranged in two columns. Some columns contain one set of cables, while others contain three sets of cables and four sets of cables. Apply 200 A load current to the cable, and study and analyze the change of cable temperature rise under different channel laying conditions.

   The temperature of cable core increases gradually with the increase of time, showing an overall upward trend until it reaches a stable state. The more cable groups laid in the cable channel, the higher the temperature rise. There are many parallel tunnel cables, so the maximum temperature of the parallel tunnel cable is slightly higher than that of the cable in the single line tunnel. There is a temperature cycle between the two channels of the parallel tunnel, with good heat dissipation capacity, and the cable core temperature will be reduced. The two channels of parallel pipe jacking are close to each other, and the temperature cycle is not significant. Therefore, the interaction of the two channel temperatures is the main influencing factor, making the cable temperature rise higher.

    Parallel tunnels far away from each other can effectively reduce the maximum temperature rise of the cable core. The four-circuit cable group laying method can make efficient use of the cable channel space, and the temperature rise is only slightly higher than the three-circuit cable group laying method.