Mechanics Analysis Of Protective Net Structure In UHV Crossing Construction

Protective net structure is of great significance for the safety protection of the crossing installation of overhead conductors and ground wires in Ultra High Voltage Engineering(UHV).At present,the mechanics analysis of carrying cable is usually simplified to calculate by the model of single cable in engineering.For more in line with the actual state,the influence of insulation rod and insulation net is considered.The models of protective net structure with single cable,double cables and treble cables are built by the finite element software.The mechanical properties of protective net structure are analyzed in different work conditions.The comparison of the numerical results with the theoretical results shows that the numerical method of double cables and multiple cables structure has a greater advantage.The effects of related parameters on protective net structure are summed up for providing reference of crossing construction and improving the safety of construction.The results show that the sag and tension of carrying cable both increase with the increase of span.With the increase of pre-tension,the sag of the cable decreases and the tension increases.The height-span ratio has more influence on the lowest point of the carrying cable,and has less influence on the sag and tension.With the increase of height-span ratio,the lowest point fast approaches to the lower hanging point.The distance from impact location to center has linear proportional relationship with sag and tension in accident condition.With the increase of the distance between carrying cables,the sag and tension increase significantly.With the increase of carryin g cable diameter,the sag decreases,the safe distance between protective net and crossed object increases,but the tension increases sharply.With the increase of wind load,the sag and tension of carrying cable both increase.The vertical wind load makes the sag and tension increase compared with the lateral wind load.Whole protective net has to take on greater tension than partial protective net,however,the ability of the former to bear impact load is significantly stronger than that of the latter.Finally,the relevant specification of protective net structure design is analyzed in crossing construction.The maximum allowable span is obtained for different Dyneema rope specification when different wire unfolding modes are adopted.And the sag and tension of carrying cable are given within the maximum allowable span range.