Design And Security Research Of The Promotion-Demotion Subway Entrance Roof

Metro is an important tool for urban traffic.The subway entrance is not only an integral part of the subway,but also the city's landscape.The subway entrance is usually classified as shep-type entrance or non-shep type entrance.While the shep-type entrance could shelter passengers from the rain and wind during raining days,the non-shep type entrance could make passengers close to nature to enjoy the sunshine during sunny days,and non-shep type entrance is much more cheaper than the shep-type entrance.Hoever both type of the subway entrance have shortcomings.The lifting roof of the subway entrance,designed in this paper,could have the anvantages of both types of the subway entrance,it will not only get back the roof,acting as the non-shep type entrance to benefit the ventilation and lighting of the entrance,when the weather is fine,but also hoid on the roof,acting as the shep type entrance to shelter passengers from the rain and snow,during bad weather.This paper designs the promotion-demotion subway entrance roof,using the 1:5 of the real size of the subway entrance, and makes deep security reaserch for the roof.The design has used the advantage that the dead point exists in the crank rocker mechanism. During the lifting process, because of that the active components is on the support rod,the four-bar linkage do not have dead point;when the roof is at the top place,the four-bar linkage has a dead point if it falls non-normally,at which time the active components is on the beam.At the dead point,no matter how much torque applied to the beam,the four-bar linkage will not move.This makes the promotion-demotion subway entrance roof have extremely high security and it has triple safety measures,electrical self-locking,friction self-locking and the dead point of the mechanism.This paper analyses the security of the roof,using the data and information of the worst weather in recent years in Wuhan,and find out that the minimal safety factor of the four-bar linkage lifting roof is 4.5 in working situation.In order to enhance the security of the promotion-demotion subway entrance roof,the unsubstantial place of the promotion-demotion subway entrance roof has been strengthened,which turned the minimal safety factor of the promotion-demotion subway entrance roof to 6.4. And consequently,the standard framework of the promotion-demotion subway entrance roof has been worked out.Finally,this paper makes analysis and summary for the problems which turn out during the manufacturing, installation and simulations using of the promotion-demotion subway entrance roof designed in this paper,gets valuable design experience and experimental data,and lays foudation for the design of the real size of the promotion-demotion subway entrance roof.