定向钻敷设电缆输送能力评估及提升方案OA

Directional drilling installation of cables at great depths and spans is a common method for crossing non-excavated areas.However,existing methods for assessing the ampacity of cables installed via horizontal directional drilling(HDD)do not account for the influence of deep soil temperatures,leading to underestimated calculation re-sults.To address this,the actual heat transfer process of cables installed via HDD at great depths is analyzed,dem-onstrating the limitations of conventional calculation methods.A three-dimensional temperature field simulation model is then established to evaluate the real cable ampacity.To achieve an ampacity comparable to direct-buried cables,an enhancement scheme based on high thermal conductivity material backfilling is proposed.Finally,a quasi-three-dimensional thermal circuit model considering both axial heat transfer and the effects of deep soil tem-perature is developed for rapid evaluation of the conductor hotspot temperature after backfilling with high thermal conductivity materials.Simulation results show that,under various working conditions,the thermal evaluation algo-rithm based on the quasi-three-dimensional thermal circuit model has a maximum error of no more than 2.5℃,which meets the accuracy requirements for cable thermal evaluation in engineering applications.