英文篇名
DESIGN AND APPLICATION OF SOIL NAILING AS EXCAVATION RETAINING STRUCTURE
作者
呂芳熾、周安之、謝旭昇、林永光
摘要
土釘(Soil Nailing)為歐美最近二、三十年來所發展之現場土壤加勁技術(In-Situ Soil Reinforcement Technique),藉由密間距之加勁材(Inclusion)配合面版(facing),將現場土壤加勁形成一穩定之現場重力結構,如圖一所示,並增加土壤之抗剪強度,以抵擋因施工或其他因素改變土壤內之力系所造成之作用力。依Bruce,Jewell(1986)之描述,現場土壤加勁技術可區分為(1)土釘、(2)微型樁(Micropile)、(3)土釘筍(Soil dowel)三種,其使用之範圍隨土壤之坡度由陡至平緩而漸從土釘轉變為土釘筍,其間三種加勁材隨滑動面與加勁材之夾角不同而影響其受力行為,由土釘之拉力,至微型樁之剪力及彎矩,最後之土釘筍之剪力作用(Schlosser,1982)。而由圖二更可比較此三種現場土壤加勁技術異同之處。土釘雖是最近發展之工法,但已被廣泛運用於各種土木工程上,包括邊坡穩定、基礎開挖、橋台(Abutments)及隧道出入口處及其週邊之護坡工程,圖三即為土釘被運用於各種土木工程上之示意圖,其實國外亦有施工案例,將士釘運用瀕臨破壞或變形過大之擋土結構之修補(Remediation)加強工程上。本文將淺略介紹土釘之施工方式,土釘擋土措施之設計與行為,並簡略介紹一施工實例,將土釘配合噴漿運用於安山岩塊層之基地開挖,達到安全性與經濟性之要求。
英文摘要
Conventional excavation retaining structures such as diaphragm walls, sheet pile walls, soldier piles, etc., were found to be unsuitable for use in dense ground. In Taiwan area, andesite debris in northern Taipei and gravel in Taoyuan/Chungli may be regarded as dense ground, and soil nailing appears to be a viable alternative in these subsoil conditions. Soil nailing can be categorized as in-situ soil reinforcement technique, which utilizes closely spaced inclusions and facings to strengthen in-situ ground. This technique has found wide acceptance in such areas as slope stabilization, fuondation excavation, etc. Mechanism and design principles of soil nailing are addressed in this Paper, a deep excavation project with the application of soil nails is also presented.