Study On Wind-induced Response And Bearing Performance Of Transmission Tower-line Systems Affected By Ground Surface Deformation

Surface movement and deformation caused by coal mining has always been a major hidden danger to the safety of transmission tower-line systems in mining areas in China.In recent years,local extreme weather disasters,such as downburst,have occurred frequently in mining areas such as Shanxi Province,which has done further serious harm to transmission tower-line systems in mining areas.Therefore,it is of great significance to study the wind-induced response and failure mechanism of transmission tower-line systems in mining area under the combined action of surface deformation and boundary layer wind or downburst.The specific research contents and main achievements of this paper are as follows:The finite element models of 110 kV,220kV and ±800kV typical transmission tower-line systems are established,and the influence of grid sizes on the stress of the members and the reaction force of the support was analyzed.Based on modal analysis,the influence of the wires on the Vibration modes and frequencies of typical tower-line system was obtained.Based on the spatial correlation of fluctuating wind speed,the layout method of wind speed simulation points on typical transmission tower-line system was proposed.The wind load models of boundary layer and downburst were proposed,and the wind speed of boundary layer was simulated by linear filtering method.The average wind speed of downburst was obtained based on Vicroy model.What's more,the fluctuating wind speed of downburst was obtained based on Kaimal wind speed spectrum and evolutionary spectrum harmonic superposition method.The wind load time history functions of boundary layer wind and downburst were obtained by conversion.Taking three typical transmission tower-line systems with different voltage levels as objects,the mechanical deformation characteristics and failure modes of transmission towerline systems in mining area were analyzed under the action of surface deformation by considering different types of surface deformation and different directions of surface horizontal deformation.The anti-deformation performance of typical transmission tower-line systems under different surface deformation was obtained,and the influence of horizontal deformation directions on the anti-deformation performance of tower-line systems was revealed.Considering the effects of boundary layer wind with different wind directions and surface horizontal deformation in different directions,the influence of surface deformation directions and degree on the resistance of tower-line systems to boundary layer wind was analyzed and revealed.The variation rules of wind-resistant capacity of tower-line systems under different wind directions and the most unfavorable wind directions corresponding to different surface deformation directions were obtained.At last,a safety assessment method of transmission tower-line systems under boundary layer wind in mining area was proposed.Considering the effects of different moving paths of downburst and different directions of surface deformation,the variation rules of stress of the members and displacements of control point of the tower-line system under downburst were analyzed,and the influence rules of surface horizontal deformation directions and degree of surface deformation on wind-resistant capacity of tower-line systems were obtained.The safety assessment method of transmission tower-line systems under downburst in mining area was put forward.