| Fire-fighting facilities in small mountainous cities can usually meet most of the city's fire-fighting needs.However,in the event of an earthquake disaster,the risk of earthquake secondary fires increases the difficulty of fire protection in urban buildings.For example,the obstruction of Fire-fighting channel and the destruction of municipal water supply network will narrow the service scope and reduce service intensity of fire-fighting facilities.A quantitative evaluation on the post-earthquake service efficiency of fire fighting facilities in small mountainous cities can surface where does the problem lie in and then ulteriorly improve the post-earthquake fire protection in such cities,reduce the loss of people's lives and property.Through literature review and spot investigation,earthquake-induced fire probability model of single building,probability analysis method,model of seismic damage prediction,software platform of AutoCAD and ArcGIS as well as some other related theoretical methods and software technologies were applied in this study to research the post-earthquake service efficiency of fire fighting facilities in Dongchuan city.First,establish a service efficiency evaluation method for fire fighting facilities in Dongchuan city.(1)Based on Professor Ma Donghui's method for assessing the probability of a single-building fire accident,the ArcGIS software platform will be used to evaluate the risk level of secondary fires in Dongchuan city.The factors of the secondary earthquake fire disaster will be evaluated from the probability of structural risk and functional risk,that will be amended by major fire hazard sources.The fire protection demand of Dongchuan city buildings in mountain areas is finally quantified on the basis of the results of the evaluation.(2)Tao xiaolin's seismic damage model of mountain city traffic system is applied to evaluate the post earthquake connectivity probability of fire channels under different seismic intensity.On the basis of it,the post earthquake service scope and service intensity of the fire station are evaluated.According to the experimental method of seismic damage of Japanese waterway Association,coupled with the assessment of seismic vulnerability of municipal water supply networks in Dongchuan city,municipal fire hydrants in well operation under different seismic intensity are evaluated to quantify the the service scope and service intensity of them.(3)In accordance with?code for fire protection design of buildings? fire water flow to determine the city building fire rating of the traffic demand,andthen respectively under different earthquake intensity,fire station,fire hydrant,fire water service compared with building fire demand flow intensity,evaluation of fire station under different earthquake intensity,the service efficiency of fire hydrant;Moreover,the service scope of fire station and fire hydrant is superposed,which compares the service strength of the overall fire-fighting facilities with the demand of construction fire flow,and evaluates the supply and demand relationship between them.Secondly,according to the evaluation method established in the previous article,the empirical study will be carried out on the Dongchuan District of Kunming.To construct a distribution database of buildings,roads,water supply networks and fire fighting facilities in Dongchuan District by AutoCAD and ArcGIS.And then evaluate its fire protection demand as well as service scope and service intensity of the fire fighting facilities respectively on the basis of seismic damage evaluation.At last the service efficiency of fire fighting facilities after the earthquake will be evaluated by comparing the fire protection demand with the fire service ability.According to the study,in Dongchuan city,the buildings in the "low" and "lower" risk levels accounted for 77.46% and 22.54%,respectively,at the earthquake intensity of 6 degrees and below.When the earthquake intensity was 7 degrees,the buildings in the "low","lower" and "middle" risk levels accounted for 38.34%,58.88% and 4.78% respectively.In the earthquake with an earthquake intensity of 8 degrees,the buildings in the "low","lower","middle" and "high" risk levels accounted for 38.34%,0.01%,61.61% and 0.04% respectively.When the earthquake intensity was 9 degrees,the buildings in the "low","lower","middle" and "high" risk levels accounted for 38.34%,0.01%,43.05% and 18.60% respectively.The construction fire demand flow is mainly 15L/S,only 22 buildings meet the demand of 20L/S,and 6 buildings meet the requirements of 25L/S.In earthquakes ranked 9 degree,8 degree,7degree,6degree and below,the service area of the fire station accounted for 17.18%,16.64%,15.76% and 12.09%;the amount of buildings with service efficiency of 100% account for 70.66%,66.67%,62.80% and 44.11%.And in earthquakes ranked 9 degree,8 degree,7degree and below,the service area of the fire hydrant account for 17.18%,16.64%,15.76% and 12.09%;the amount of buildings with service efficiency of 100% account for 17.00%,8.52% and 0%.When the service scope of fire station and fire hydrant are superposed,the overall service scope and service efficiency of fire fighting facilities in Dongchuan District are in accordance with that of the fire station,which shows that the service offire hydrant is completely overlapped by the fire station.While the service scope and efficiency of fire fighting facilities will be greatly reduced with the increase of earthquake intensity.Especially when the earthquake ranked 9 degree occurs,the service coverage of buildings is less than half of that of the whole city.Finally,the results of this study show that for buildings in central urban area and new city zone,because of the high quality,low intensity and high aseismic grade,the risk of earthquake secondary fires is low,the water supply demanded for fire fighting is large,and the fire channel has high post earthquake connectivity,and fire fighting facilities have broad coverage and high intensity.While in the old city zone and the marginal administrative village of the planning area,the risk of earthquake secondary fires is high,the water supply demanded for fire fighting is small,and the fire channel has ineffective post earthquake connectivity,and fire fighting facilities have narrow coverage and low intensity because of the low quality,high intensity and low aseismic grade of buildings.Fire fighting facilities in small mountain cities are featured with the high overlap rate of fire fighting facilities,small coverage area and high intensity of water supply in the service area.But the service efficiency of the whole fire fighting facilities is low,coupled with a large fade zone.Moreover,with the increase of earthquake intensity,the service scope and efficiency of facilities in such cities will decrease,so do the service fade area.Especially when the earthquake ranked 9 degree occurs,The service blind area is increasing rapidly,and the building risk level in the service blind area is mainly "middle" and "high" risk building,the supply capacity of fire services will be greatly reduced. |
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