Simulation Research On Space Environment And Emergency Evacuation Of Underground Rail Transit Hub Based On BIM Model

Underground rail transit is in the stage of rapid development and construction.How to improve the service level of rail hub to ensure the traffic capacity of the system has important research significance.Based on the BIM three-dimensional information model,this study focuses on the design requirements of spatial light,sound and air environment of underground rail transit hub and the key problems of emergency evacuation.The main research contents are as follows:First of all,according to the spatial characteristics of the indoor space of the underground rail transit hub,the design requirements of the hub lighting,acoustics and air environment are analyzed.Aiming at the problems of experience dependence and low visibility of traditional design methods,this paper puts forward the research method of indoor space of underground rail transit hub based on BIM model,and establishes the basic civil BIM model based on Bentley software,which provides the basic research method and BIM model foundation for the follow-up research of indoor space environment and emergency evacuation.Secondly,the illumination standard value,illumination uniformity and design glare value parameters are set for the established lighting environment spatial model.Through visual analysis,it is found that the illumination uniformity of the uniform layout scheme is 2.1 times that of the compact layout scheme.For the uniform layout scheme,it is found that the UGR in the direction of parallel principal axis is 10% smaller than that in the vertical direction;The average illuminance increased from 200 lx to 300 lx,and the proportion of illuminance redundant area decreased from 22.13% to 0.11%.Through BIM illumination simulation and data regression,the functional relationship between lighting unit density and UGR and the three-dimensional quantitative evaluation method of illumination uniformity are established.Thirdly,the number of passengers,noise source and sound absorption parameters are set for the established acoustic environment space model,and the reverberation time analysis based on BIM acoustic environment simulation model is realized.The total equivalent sound absorption area is introduced to quantitatively evaluate the applicability of the three reverberation time calculation formulas,The influence of sound-absorbing materials on the reverberation time of platform space is quantitatively analyzed.For the main noise frequency of the hub is 500 Hz,compared with the scheme without sound-absorbing material,the reverberation time of the scheme with sound-absorbing material is reduced from 7.17 s to 0.28 s,which is far less than 1.5s required by the specification.Fourthly,the ventilation design index suitable for underground rail transit hub are put forward.In view of the gaps in the current specifications,a BIM three-dimensional ventilation model based on PMV-PPD index is established.The research shows that the PMV-PPD index is the best when the indoor average temperature is 24 ℃ ～ 26 ℃ and the indoor average wind speed is close to 0.3m/s.The effects of different air supply direction,speed and temperature are quantitatively analyzed,and the recommended scheme is given.When the air supply direction is vertical,the air supply temperature should be 24 ～ 26 ℃ and the air supply speed should be0.8m/s;Under the parallel air supply direction,the air supply temperature shall be set at 22 ℃and the air supply speed shall be 1.4m/s ～ 1.6m/s.Finally,the emergency evacuation capacity of the hub is studied based on BIM model.The established emergency evacuation simulation space model is set with passenger density,passenger characteristics and equipment status.The simulation shows that the total escape time under the condition of passenger independent escape is 415 s,which is much longer than the optimal escape time of 271 s.According to the time-space simulation distribution of personnel,the main reasons for the limited traffic capacity in the actual situation are analyzed.Based on the problems found,an exit oriented passenger marshalling evacuation scheme is proposed,and the hub emergency evacuation situation adopting this scheme is simulated,which shortens the time for all passengers to escape from the hub from 415 s to 316 s.The real-time planning method of emergency escape path based on Dijkstra algorithm is established to improve the overall traffic capacity of the hub.To sum up,this paper comprehensively uses BIM integrated information to simulate lighting,acoustics,ventilation and emergency evacuation,so as to provide visual and digital reference for hub construction.The research results are helpful to further establish the full life cycle BIM Technology Application System,and are of great significance for the improvement of space environment and emergency evacuation capacity of underground rail transit hub.