[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-109-1-fire-science-028":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-109-1-火災學概要-028","fire-109-1-fire-science-028",109,1,28,"森林火災的種類與敘述，下列何者正確？",{"A":16,"B":17,"C":18,"D":19},"樹幹火主要燃料為茅草與灌木，為森林大火的主因","地表火主要由含樹脂之樹木燃燒造成","樹梢火通常在開放環境中燃燒","地中火通常由地表火而來，有大量有機可燃物","C",null,[],false,"本題考點：森林火災依燃燒部位區分為地中火、地表火、樹幹火與樹梢火(樹冠火)，各自的燃料與燃燒環境差異。\n【正解理由】樹梢火燒的是樹木頂端的枝葉與樹冠層，位置遠高於地表、四周無遮蔽物，屬於開放環境中的燃燒，供氧充分且直接暴露於風場，因而蔓延速度快、常出現越過空隙的跳躍延燒，是森林火災中最猛烈也最難控制的型態，故選 C。\n【逐項排除】\n(A) 錯誤。茅草、灌木與地被枯枝落葉是地表火的燃料，不是樹幹火；樹幹火燒的是樹木主幹與樹皮，多由地表火沿樹幹向上延燒而成。\n(B) 錯誤。含樹脂之針葉樹因油脂易揮發、發熱量高，是樹梢火迅速擴大的助因；地表火的燃料為地面上的乾草、落葉與表層腐植質。\n(C) 正確。樹冠層位於林木上部的開放空間，火勢在此以明火快速蔓延，受風速與地形影響最劇。\n(D) 錯誤。地中火燃燒的是地表以下的腐植層與泥炭層，屬缺氧的無焰悶燒，須具備深厚且乾燥的有機質層才可能發生，蔓延極慢、發生頻率也最低，把它說成「通常」承接地表火而來，是把偶發情形當作常態。\n【記憶點】由下而上背四層：地中悶燒、地表草葉、樹幹主幹、樹梢在開放空間燒得最猛。","森林火災的分類邏輯是「燒到哪一層」，四種型態各有燃料床、燃燒型態與控制難度。地中火(地下火)燒的是地表以下的腐植質與泥炭層，氧氣供應受限，以無焰悶燒方式緩慢向四周推進，火線常看不見煙焰卻能持續數週甚至跨季，撲滅必須開挖或大量注水浸潤，屬於典型的深層火勢。地表火燒的是地面上的枯枝落葉、乾草與灌木，是最常見的起火型態，蔓延速度中等且火焰高度有限。樹幹火由地表火沿粗糙樹皮、樹脂或枯死枝條向上竄升，是地表火升級為樹梢火的橋梁。樹梢火(樹冠火)在樹冠層之間連續蔓延，因位於開放大氣中而供氧無虞，火行為受風速主導，可越過道路、溪溝形成飛火，撲救時人員難以接近。\n\n影響火行為的三大因素是燃料、氣象與地形，考題常以「火環境三角」出題。燃料方面看含水率、粒徑與連續性，細小乾燥的死燃料引火最快；氣象方面看風速、相對濕度與長期乾旱指數，強風不但供氧也把火焰壓向未燃燃料；地形方面則有著名的「上坡火快、下坡火慢」——上坡時火焰對坡上燃料的預熱面積增大，蔓延速度隨坡度增加而顯著上升，這與煙囪效應同理。\n\n易混淆對照：地中火與地表火的關鍵差別在有焰與無焰，前者是缺氧的陰燃、後者是有焰的擴散燃燒；樹幹火與樹梢火的差別在燃燒部位是單株的主幹或整片的樹冠層，前者仍屬垂直延燒的過渡階段，後者已形成水平連續的火線。另一組常混淆的是「地中火」與建築火災的「深層火勢」，兩者都是缺氧無焰、內部蓄熱的燃燒型態，都不會出現在火勢全面發展的最盛期，而是出現在初期或長時間持續的階段，這也是火災學跨章節連結的常見考法。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-109-1-fire-science-027","下列有關泡沫滅火劑，何者敘述正確？",27,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-109-1-fire-science-029","有關防火塗料敘述，下列何者錯誤？",29,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-109-1-fire-science-026","閃燃發生時間之影響因素中，通風為其中之一項，請問：A0(H0)1\u002F2 的通風因子公式中，A0 與 H0 各代表何意？",26,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-109-1-fire-science-030","海龍替代滅火藥劑中，下列何者在大氣之滯留時間最久？",30,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-109-1-fire-science-025","有關火羽流的敘述，下列何者錯誤？",25,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-109-1-fire-science-031","建築物火災在閃燃發生後之全盛期火災的特性，不包括下列何者？",31,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-111-1-fire-science-028",111,"通風控制燃燒下，居室內有可燃物 1200 kg，該居室有一開口面積 6 m2，高度 2 m，則火災持續時間約幾分鐘？",{"webId":58,"year":59,"stem":60,"number":13},"fire-110-1-fire-science-028",110,"下列有關電器用品「焦耳熱」之敘述，何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-108-1-fire-science-028",108,"火場中煙霧的成分複雜且多具毒性，火災時若吸入下列何種氣體，會妨礙細胞中氧化酵素之活性，造成細胞呼吸停止？",{"webId":66,"year":67,"stem":68,"number":13},"fire-107-1-fire-science-028",107,"下列何者並非古蹟火災防護之特性？",{"webId":70,"year":71,"stem":72,"number":13},"fire-106-1-fire-science-028",106,"有一平板絕緣層內面溫度為 270℃，外面以熱對流方式散失到 20℃的空氣中，平板厚度為 4 cm，熱傳導係數 K=1.2W\u002Fm℃，若要使平面外面的溫度不超過 70℃，試求其對流熱傳係數的極小值？",1785123162903]