Study On The Design And Control Of The Air Environment In Deep Underground Space Safety Islands

As society continues to develop and urbanisation accelerates,the development of shallow,fragmented and passively developed underground space is insufficient to support the sustainable development of cities in the future.In order to alleviate the contradiction between urban land supply and demand,improve urban environment and traffic,and promote sustainable urban development,urban underground space development is gradually progressing to deeper spaces.Due to the strong confinement of deep urban space,the difficulty of interaction with the outside world,the high risk of disaster and the difficulty of vertical evacuation,people cannot quickly reach the surface,so it is necessary to build safety islands to ensure the safety of the lives of people evacuated in deep space.This paper presents a design method for the air environment in a safe island in a deep urban space,with reference to the functional planning and human activities in the deep urban space.Using the rectangular safe island survival room as the research object,the best air supply scheme and air supply parameters to guarantee the thermal environment in the survival room are obtained through the study of different air supply schemes and air supply volumes in the survival room;the best air supply scheme and air supply volumes to guarantee the air quality in the survival room are obtained through the simulation of different air supply schemes,air supply volumes and the metabolic rate of people in the survival room.The specific scientific work is as follows:（1）Propose the protection concept of safe islands in deep urban space.Based on the personnel density and service demand of urban deep space,three types of 100-person safe islands applicable to different places are established-rectangular safe island,square safe island and concave safe island.Determine the environmental parameters that guarantee the survival of people in the safe island,such as temperature and humidity,air cleanliness,oxygen content,etc.,and give the design method of the air environment in deep underground space safety islands with 100 people rectangular safe islands as an example.（2）Designed for different air supply solutions in a rectangular safe island for 50people survival room.Numerical simulations of different air supply solutions were conducted to analyze temperature,temperature gradient,velocity,inhomogeneity coefficient,ventilation efficiency,O₂ concentration and CO₂ concentration,etc.The best air supply solution to ensure the thermal environment and air quality in the survival room is the"Vertical wall+top plate"attached ventilation.（3）Numerical simulations were conducted to study the effects of different air supply schemes,air supply volumes,and personnel metabolic rates on air quality in a 50-person survival room in a rectangular safe island.The study shows that for the 50-person survival room,the air quality in the survival room can meet the survival of the distressed personnel when the air supply volume per person in the survival room is 0.1 m³/min,the O₂concentration in the survival room is controlled at 20.65%,and the CO₂ concentration is controlled at 0.315%,without considering the air supply cooling condition.（4）Change the air supply parameters of the air supply scheme of"Vertical wall+top plate"attached ventilation,analyze the temperature,speed and other indicators of different sections of the personnel activity area in the survival room,and determine that when the air supply speed is 3 m/s and the temperature is 22℃,the thermal environment in the survival room can meet the personnel survival.Through the above research,the evacuation problem of people in the deep underground space of the city is solved,the life safety of people in distress in the deep space is guaranteed,and the technical reference is provided for the air environment control in the safe island of the deep underground space of the city.