科研之友
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摘要
The most common location for campsites is in forested or arborous areas. Given the regular use of combustible material by campers and the frequent use of campfires to cook, campsites become areas with a high propensity for the occurrence of fires. Moreover, fires occurring close to campsites can cause evacuations, disturbing their regular activities and jeopardizing tourism and likewise economic activities. While some campsites have tents and caravans within a secure distance of each other, many other campsites have the tents and caravans very concentrated in a limited area, making it much easier for fire to spread from a tent to the next. Despite the occurrence of several of these events, the associated risk is currently not well studied or documented. The work presented in this paper was performed within the Portuguese research project FireCamp, whose main purpose was the analysis and documentation of the fire risk in campsites. Several topics were addressed and some of them will be presented within this paper, specifically: (1) understanding of the mechanisms associated to burning tents; (2) analysis of the combustibility of typical accessories used in campsites such as tents, sleeping bags or camping mattresses; (3) characterization of a campsite fuel cover and its surroundings via image analysis taken by unmanned aerial vehicles; and (4) modeling of fire spread in campsites. A pilot study was carried out between 2011 and 2014 in the Campsite of Cja, in Arganil-Coimbra-Portugal. Taking into consideration that external fires frequently threaten these sites, complementary to the analysis of the fuel distribution inside the campsite, the land use analysis in the surrounding area is also of great interest. Thus, a fuel map of the Campsite of Cja was produced based on a high-resolution map of the area obtained by aerial photography produced by drones. Based on this fuel map, a stochastic model was set up to predict the fire spread in the covered area. The results obtained in this pilot study are hereby presented. Additionally, several laboratory tests were carried out in order to analyze the high calorific values (HCV) and the time to ignition (TTI) of the materials of typical camping accessories. The values of HCV found are in the range of 22.45-45.45 MJ kg(-1) and the values of TTI found are in the range of 118-224 s. These values show a high propensity for these materials to spread fire. Real tents with and without typical accessories inside (e.g., sleeping bags) were burnt in controlled environment in order to determine the mass loss decay, the increase of temperature and the convective airflows produced. Due to the convective flow inside the tent, these parameters were not considered as valid but these tests were important to understand the mechanisms associated to the burning of tents and the risk associated. The presence of combustible material inside a tent was found to be of high importance in order to sustain the combustion.
- 出版日期2017-3
