Study On Up-going Evacuation Efficiency Of Slope Of Stair In Underground Space

In order to expand urban space and alleviate land pressure,China’s underground space development and construction has entered a stage of rapid growth.The shallow underground space in many cities is gradually becoming saturated,and the development of underground is becoming deeper and layered.However,with the development of the depth of underground space and the increase in the number of users,the hidden dangers of safety accidents in underground space have also increased,which has brought great challenges to upward evacuation.At present,stairs are still the most important,most reliable and most effective means of evacuation in underground space ascending,and the slope of stairs is directly related to the gait of evacuees,which will have a major impact on evacuation efficiency.The current domestic regulations stipulate the minimum step width and maximum step height of buildings with different functions.Under the premise of complying with the specifications,architectural designers mainly consider economic factors such as the use of building area when designing stairs.It is more likely to cause personnel fatigue,so the need for the current code to suit the evacuation needs to be studied.In the past,studies on the slope of staircases focused on the comfort and safety accidents of daily use of personnel,and less research on evacuation efficiency.Therefore,it is of great significance to study the slope of the stairs during upward evacuation.The purpose of this study is to analyze the influence of the gradient of the stairs on the upward evacuation and explore the possibility of optimizing the evacuation efficiency.First,the article analyzes the typical characteristics of upward evacuation of underground space,and sorts out the norms of underground space depth division and the concept of evacuation time.Based on this,the article summarizes and analyzes the research status from the two topics of stair slope and upward evacuation,and reviews the literature with the advancement of research methods and the innovation of research conclusions.Eventually,the existing problems in the research status were discovered,basic judgments were made,and Research framework were established.Secondly,the author conducts a sample survey on the status quo of the underground space evacuation staircases in the central business district of Chongqing and the design parameters of evacuation staircase slope,underground space depth and underground space building layer height are described and inferred statistically,The present situation of evacuation staircases in underground space in chongqing is explored and the design basis is provided for human observation experiment and evacuation simulation.Thirdly,the author conducted observation experiments on real people and simulation studies,then compared and analyzed the evacuation time,evacuation speed and fatigue degree of people on stairs with different slopes.This paper mainly studies the influence of stair slope on the evacuation speed of single person ascending,the fatigue degree of movement of personnel and the evacuation time of group.The quantitative analysis and qualitative judgment of the collected data were made by means of statistical analysis,and the mathematical model of the relationship between the stair slope and the ascending evacuation velocity was built.In the end,the paper makes a contrastive analysis of the current standard,the design status and the research conclusion,and puts forward some optimization countermeasures,such as the recommended slope value of stairs in underground space.