| Since the reform and opening up,the development of China’s social productive forces and the progress of science and technology have accelerated the urbanization.Besides,with the urbanization,the color steel plate,as a new building material,has been widely used in field operation and construction houses,temporary offices and dormitories on construction sites,temporary commercial or other buildings in urban municipalities,etc.Thus,the buildings with color steel plate are widely distributed in urban villages,urban-rural fringe,industrial parks,etc.Color steel plate buildings have become an indispensable space carrier in the specific development stage of urbanization,which have remarkable space-time accumulation,distribution and evolution characteristics.Currently,the research on color steel plate buildings is mainly based on various statistical data,focusing on urban renewal,fire,materials and safety,while,there is little literature on its space-time evolution law and its relationship with urban fire protection and environmental pollution.Therefore,with the color steel plate buildings in the urban area of Lanzhou as the research object,this study systematically studied the space-time evolution of color steel plate buildings with different levels,types and ranges,the color steel room coating decomposition and environmental pollution,as well as the fire risk prediction and fire rescue,according to the spatial statistics and quantitative analysis methods such as RS,GIS,geography,environmental science,urban planning,etc.The results showed the following:(1)A U-Net neural network model with self-attention mechanism was designed for color steel plate building automatic extraction.This study deeply studied the method of extracting color steel plate building information from high resolution remote sensing images,adding a self-attention mechanism to the traditional U-Net neural network model,which could realize the automatic extraction of color steel plate building information from GF-2.All evaluation index values met the practical application requirements.(2)The space-time evolution characteristics and laws of the color steel plate building complex in Lanzhou were systematically analyzed.This study explored the spatial characteristics of color steel plate buildings in terms of space-time scale,such as spatial quantity distribution,distribution center of gravity,spatial distribution direction,aggregation and compactness,analyzing the change law of its time sequence.The results showed that from 2013 to 2021,the number of color steel plate buildings in the study area generally increased first and then decreased,but there were differences among regions.In 2017,the number of color steel room buildings was the most.(3)The decomposition characteristics and spatial distribution characteristics of color steel plate architectural coating were quantitatively studied.The color steel plate building coating aged rapidly with the wind and sunshine,which not only affected the service life of color steel plate buildings,but also produced some harmful gases in the decomposition process.This study carried out the simulated aging process of color steel plate buildings in the laboratory,measuring the composition and volatile quantity of gases.On this basis,the spatial-temporal aggregation of these harmful gases in the study area was attempted to be studied.It showed that the natural decomposition of color steel plate building coating affected the atmospheric composition in the high concentration area of color steel plate buildings,but the total amount was less,which had small effect on the environmental pollution.(4)The spatial layout of urban fire stations was optimized.Based on the data of POI,fire accidents and industrial parks in Lanzhou,the "location-allocation" model was applied to assess the fire risk in the key areas of the color steel plate building complex in the built-up area of Lanzhou.The short-term and long-term space optimization of fire stations were carried out through the fire safety standards.It was found that the coverage rate of high fire risk areas at existing fire stations was low,which needed 4 more fire stations in the short term and 17 new fire stations in the long term to achieve the maximum coverage of high fire risk areas.In general,this study revealed the derivative relationship between the color steel plate building complex and the urbanization process through the automatic extraction of the information on the color steel plate building complex as well as the study of the temporal and spatial evolution law.Furthermore,it analyzed the potential safety hazards of the color steel plate building complex to the city through the study of the fire risk and the influence of coating aging and decomposition.The research methods and results provide data and method support for urban planning,management and urban fire protection. |
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