Experimental Study On Mechanical Behavior And Monitoring Indexes Of High-voltage Cable Ducts Bank And Cable Trench Structure

High-voltage cable duct bank and cable trench structures are the most common laying modes in high-voltage cable lines.With the growth of buried laying,cable ducts and cable trench structures have been widely used.In the meantime,there have been various disease and damages with different degrees.This article explores the mechanical behavior of high-voltage cable duct bank and cable trench structure by conducting multiple tests of different control groups,and gives suggestions on structural selection,monitoring indexes and program selection,which provides guidance and theoretical basis for the monitoring and operations of the high-voltage cable duct bank and cable trench structure.The main research contents and conclusions of this paper are as follows:(a)In view of the limited research and specification on the failure mode and mechanical behavior of cable piping and cable trench structure,the field research and investigation on the cable piping and cable trench structure of cable lines with existing diseases were carried out.According to the investigation and summary of the current cable lines in the cable piping and cable trench civil structure of the main form of disease and the cause of disease,it was provided reference for cable piping and cable trench structure of the follow-up research.(b)The results of cable piping test with or without structural reinforcement and two different laying types were compared,the overall failure mode was similar to that of the less reinforced beam,and the extension of the cable protection pipe along with the main crack would also be bear the tensile stress and eventually failed.The flexural capacity of the internal cable protection pipe and the underlying soil layer to the cable piping structure was significantly improved,which could avoid the failure of the internal cable protection pipe to bear the tensile stress prematurely and then squeeze or stretch the cable inside the protection pipe.(c)The test results of cable trench joints with three stress modes and two strength of plug joint cement mortar were compared.When the external load is dominated by shear force,the failure form of expansio n joints would present brittle "up and down dislocation",and the failure form of expansion joints would present ductile "open at both ends" when the bending moment was dominant.It was more unfavorable conditions of structural steel that the cable trench cover was under pressure and the structure at the expansion joint was sheared,however,increasing the strength of plug joint cement mortar could effectively improve the bearing capacity of expansion joint.(d)Based on the mechanical behavior and failure mode of the high-voltage cable trench,the applicability analysis and suggestions were made for the selection of the two types of laying,in addition,the relationship between the monitoring index and the suggestion and the relationship between the monitoring index and the safety state of the structure were put forward.For the cable piping structure,the concrete damage status of the cable piping structure could be comprehensively determined by the monitoring indexes such as internal cable protection pipes and reinforced concrete,so as to realize the safety monitoring and early warning of the structure.