基于雪荷载对于农用设施大棚倒塌气象风险评估

Meteorological Risk Assessment of Agricultural Greenhouse Collapse Based on Snow Load

摘要: 研究2024年低温雨雪冰冻天气对农业生产的影响，构建蔡甸区钢筋大棚不同相态下降水致灾的气象预警指标、探讨冬季低温雨雪冰冻导致大棚倒塌的应对措施具有现实意义。为此，以武汉市蔡甸区为研究区域，基于蔡甸区气象观测站逐日气象资料，钢架大棚，结合农作物、塑料大棚灾情资料，采用有限元建模的方法，引入安全系数的概念。结果表明：Q235A型钢管的钢架的最大承载风荷载为9级风，最大雪荷载积雪厚度为9.6 cm；本次雨雪冰冻过程中关键致灾因子：“底冰上雪”，即先下冻雨形成光滑冰壳道中(无法滑落)，再覆盖积雪，由此产生的垂直荷载约为0.67 KN/m²，远超农业大棚极限承载力(约0.28 KN/m²)，直接导致大棚结构性坍塌；通过实地调研走访，因为基础不牢、钢管锈蚀、管细壁薄、安装方式不科学等非气象因素的原因大大降低了大棚的承载力，引入安全系数，得到塑料大棚致灾的气象临界阈值，冻雨阈值为1 cm，冻雨阈值为2 cm，冰粒纯雪深度阈值为5 cm。

Abstract: It is of practical significance to study the impacts of low-temperature rain, snow and freezing weather on agricultural production in 2024, establish meteorological early warning indicators for disasters caused by different phases of precipitation on steel-structured greenhouses in Caidian District, and explore countermeasures against greenhouse collapse induced by winter low-temperature rain, snow and freezing disasters. Taking the Caidian District of Wuhan City as the research area, this study adopted the finite element modeling method and introduced the concept of safety coefficient based on daily meteorological observation data from meteorological stations, steel frame greenhouse parameters and disaster data of crops and plastic greenhouses. The results show that the maximum wind load bearing capacity of Q235A steel pipe greenhouses corresponds to Grade 9 wind, and the maximum snow load bearing capacity is equivalent to a snow depth of 9.6 cm. The key disaster-causing factor during this rain-snow-freezing event was the formation of an ice layer covered with snow: freezing rain first formed a smooth ice crust on greenhouse surfaces that prevented snow from sliding off, followed by snow accumulation. The resultant vertical load reached approximately 0.67 KN/m², which far exceeded the ultimate bearing capacity of agricultural greenhouses (about 0.28 KN/m²) and directly caused structural collapse of greenhouses. Field investigations revealed that non-meteorological factors including unstable foundations, rusted steel pipes, thin-walled slender pipes and unscientific installation methods greatly reduced the bearing capacity of greenhouses. Combined with safety coefficient correction, the critical meteorological disaster thresholds for plastic greenhouses were determined: 1 cm for freezing rain, 2 cm for ice accretion, and 5 cm for pure snow depth.