Research On The Galloping Characteristics Of Catenary Multi-span Positive Feeder In Gale Area

Lanzhou-Urumqi high-speed railway through the five gale areas from Gansu to Xinjiang,with a total length of 1776 km.Strong wind occurs frequently in the wind areas,and the instantaneous wind speed can reach 60m/s.Affected by strong wind,the train is in great danger of overturning and derailing.The desertification in the wind areas are serious and it is easy to accumulate sand to bury the railway.To ensure the safe operation of trains,a wind-break wall is built on the windward side of Lanzhou-Urumqi high-speed railway to effectively prevent accidents such as train overturning and railway sand accumulation.However,the wind barrier blocks the incoming wind and rise along the wall,and the "wind surge" effect occurs behind the wall,resulting in a large galloping of the square feeder behind the wall.It is found through investigation that the galloping of the positive feeder leads to serious wear and tear of clues and connecting hardware,inter line discharge,disconnection,dropping and tripping,which are important hidden dangers for the safe operation of electrified railway.Firstly,according to the static stress of the catenary positive feeder,the static stress analysis is carried out,and combined with the catenary calculation formula,the relevant parameters of the constant height suspension positive feeder are deduced and calculated.In the mechanical calculation of transmission line,the stiffness of conductor is ignored and regarded as a flexible clue without rigidity.At the same time,the positive feeder is a typical suspension structure,which will deform under the influence of gravity and tension.In the finite element software,the cable element can be simulated by setting the material property of the rod element to no compression.For the design of wind tunnel test model,the geometric similarity between the overall model and the actual site is considered,and the rationality and correctness of the fluid simulation method used in this thesis is verified by wind tunnel test.Secondly,the galloping characteristics of the positive feeder of single span and multi spans catenary positive feeder are studied.Combined with the actual site,the rotational degrees of freedom of the suspension structure at both ends of the main feeder are considered in the multi spans main feeder model.At the same time,in order to verify the influence of adjacent spans conductor galloping of catenary positive feeder,the working condition that only one of the two spans positive feeders meet the galloping conditions is studied.The results show that when the wind speed is less than or equal to 10m/s,the interaction between spans of multi spans positive feeders will weaken each other’s galloping degree and make the galloping amplitude less than that of single span.When the wind speed is greater than or equal to 15m/s,the interaction between spans will aggravate the galloping degree of each other,so that the galloping amplitude and average stress are greater than that of a single span.There is serious galloping wave transmission between multi spans positive feeders,and the adjacent spans conductors will be affected by the galloping wave,and the galloping wave has a great impact on the horizontal galloping amplitude of the conductor due to the rotational freedom of the suspension clamp.Finally,in order to provide theoretical reference for the selection of spans length in the range of special tuyere such as mountain pass,valley pass,high embankment and bridge,the galloping characteristics of positive feeders with different spans lengths are analyzed.The results show that: the variation rules of the flapping characteristics of positive feeders with different spans lengths are generally similar,but the flapping amplitude and the natural frequency of half wave number in the same direction are different under different spans lengths.