土釘加勁技術具有施工成本低，施工速度快及施工彈性高等優點，主要應用 於基礎開挖及現地邊坡之穩定。藉由土釘與土體之不同勁度，土體的位移促使土 釘受拉，而土釘的拉力經由握裹力傳遞到相鄰的土體，因而對土體產生束製作 用；因此土釘於地層中之加勁機制，主要受土釘與土壤間之摩擦特性所影響。本 研究計畫以金屬製之模型土釘，埋置於霣降而成之砂土層中，透過拉出端之荷重 元量測土釘拉出力-位移關係。實驗室試驗乃以四種不同之土釘直徑，各加工成 三種不同螺紋牙距之不同表面粗糙程度，在三種不同粒徑之砂土中進行拉出試 驗。依據從土釘直徑、土釘-土壤介面粗糙度、及砂土粒徑等影響因素的試驗結 果中，找出適用範圍較廣的土釘行為模式。Soil–nailing techniques have been widely used in soil excavation and slope stabilization. The advantages of this technique are cost effectiveness, rapid construction, and reversion flexibility in construction process. The reinforcing behavior of nail is accomplished primarily by transferring axial force from the nails into the soil mass through friction (or adhesion) mobilized at the soil-nail interface. The effectiveness of soil nailing reinforcement in excavation or slope depends on frictional resistance capability between a nail and the surrounding soil. Model tests on a nail buried in sand will be carried out to investigate the pullout resistance of a nail under different nail diameter, roughness of nail surface, and diameter of sand grain. A behavior model for the pullout resistance of a soil nail will be developed to describe the pullout response of a soil nail.
