火灾的发生具有其一般规律,即由某种原因起火,引燃可燃物品,进而延烧扩大并在火灾蔓延发展过程中,不同程度地留下某些烧损痕迹。不同的物质留下的烧损痕迹也各不相同,如木材炭化、钢材变形、电线熔融、混凝土变色等。即使同一物质,火灾的烧损程度也不同,呈现出具有方向性的痕迹,如一根木柱,某一面比其他面燃烧炭化历害,那么炭化程度深的那一面必然是受热面,从而显示出受热的方向性。正是由于火灾发展过程中物质留下的带有方向性的烧损痕迹, The occurrence of a fire has its general rule that a fire ignites and ignites combustible materials for some reason, then expands and expands, leaving some traces of burning to varying extents during the development of the fire. Burning traces of different substances are also different, such as carbonization of wood, steel deformation, wire melting, such as discoloration of concrete. Even though the same substance has a different level of fire damage, there are directional signs, such as a wooden column, where one side charred more than the other side. Thus, the side that is deeply charred must be a heated side and thus show a heat The direction of It is precisely because of the fire left in the material development process with traces of burning,