![]() In addition, the optimization of cost and electrothermal performance has gradually become a research topic of interest. determined the effects of concrete mixtures on the resulting thermal resistivity. Hwang described a combined magnetothermal analysis for calculating the thermal fields of a cable duct bank taking into account the effects of structural steels. Bascom evaluated various cable and magnetic shielding configurations to minimize the resulting magnetic fields in an underground cable system along duct banks and near manholes. El-Kady and Horrocks described an efficient finite-element-based technique for calculating geometric factors for extended values of the external thermal resistance of cables in duct banks. Kellow employed a numerical procedure to calculate the ampacity and rise in temperature rise and conducted experiments to study the ampacity of cables and the thermal performance of duct banks with and without forced cooling. Nagley and Nease conducted different installations to determine the relative thermal characteristics of two types of duct banks that differed in terms of duct spacing and the amount of concrete. provided a reference for various ampacity ratings that were dependent on installation. Most previous studies on electrical duct banks have focused on cable ampacity and thermal resistivity. Ground subsidence (a) and damage (b) caused by deficiencies in concrete-encased underground electrical duct banks. Stirrups are also needed to hold the longitudinal steel in place during the placement of the concrete. The reinforcing steel is installed longitudinally at each corner of a duct bank (in cross section) and along the top and bottom. ![]() In general, all concrete-encased electric conduit duct banks contain steel reinforcement throughout their entire length. PVC spacers are also used to separate the internal conduits from concrete walls, as shown in Figure 1. These groupings of conduits are often protected by concrete casings. In a duct bank, electrical cables are typically laid out within polyvinyl chloride (PVC)/modified polypropylene (MPP)/high-density polyethylene (HDPE) conduits that are bundled together. ![]() Therefore, it is very important to guarantee the safety of these underground structures. In most cases, high-voltage underground cables are laid in a duct bank rather than being buried directly in the ground. They operate at a range of voltages reaching 400 kV. Cables can be laid under a road, across open land, or in tunnels. In London, most of the electricity supply is also transmitted via underground cables, which are traditionally found just below the road surface. In the central urban area of Shanghai, the proportion of underground cables has exceeded 80%. Overhead lines, underground cables, and substations are critical infrastructure components in electricity transmission. Finally, the evolution trends of the stress and deformation rates of HDPE conduits are recommended for the monitoring indexes and control standards of electrical duct banks. The threshold of the longitudinal curvature radius is determined to be 18000 m. The results suggest 5% and 7.5% as the deformation rate thresholds with respect to the ultimate states of serviceability and bearing capacity, respectively. An analysis of the experiment shows the effective role of HDPE conduits in improving the bending capacity of electrical duct banks. This study examines the bending behaviors of electrical duct banks subjected to monotonic vertical loading in a soil box using an advanced monitoring device to measure the conduit diameter change. The bending capacity of concrete-encased underground electrical duct banks has been the subject of considerable investigation using the load-structure method however, the role of high-density polyethylene (HDPE) conduits and the thresholds of electrical duct banks has not been fully scrutinized.
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