自承式鋼軌樁開挖工法，適用於良好地質條件下的大面積地下室 開挖工程，具有成本低廉及易於堅硬土層施工與施工快速等優點。使 用自承式雙排鋼軌樁開挖工法的主要目的，在於提高鋼軌樁擋土系統 的勁度，減少水平支撐設施的使用，提高人員施作效率、縮短施工工 期與增加開挖深度。 本研究利用離心模型試驗，藉由模擬開挖過程，探討於砂土層中 以自承式鋼軌樁擋土系統作為擋土設施時，改變雙排鋼軌樁排間距與 樁長或利用三排鋼軌樁等不同的樁排列方式，對自承式鋼軌樁擋土系 統穩定性的影響。另外亦探討在不同的開挖與貫入深度比下，不同樁 排列方式之擋土系統對鄰近地盤之影響程度。 研究結果顯示，砂土層中以自承式雙排鋼軌樁擋土系統作為擋土 設施時增大排間距或以三排樁作為擋土設施時，能有效的降低因開挖 所引致的地表沉陷、牆體變位與樁身的受力，有助於擋土系統之穩 定；而增長雙排鋼軌樁擋土系統之樁長有助於開挖深度的增加。因開 挖所引致之地表沉陷槽皆屬於三角槽型，且影響範圍皆為鋼軌樁擋土 壁壁後1.2 倍樁長。從試驗結果得知，將雙排與三排鋼軌樁擋土系統 視為一等值單排鋼軌樁擋土系統來進行穩定分析，為一可行之方法。 Self-supported soldier pile wall system is eminent for its superiority on low cost and easy construction when being applied in the vertical excavations. Its advantages are reducing the deflection of the retaining wall, shortening the working hour and increasing the depth of excavation. In this research, a series of centrifuge modeling tests were conducted to simulate the process of excavation with self-supported soldier pile wall retaining system. The simulations of various excavation depths with different spacing between the front and rear row piles in double-row-pile or the triple-row-pile wall system were being carried out to study the effects upon adjacent area. The test results show that the self-supported double soldier pile wall system can effectively reduce the surface settlement, horizontal displacement, tilt angle and maximum bending moment. In the double-pile-row retaining wall system, with the increase of the distance between the front and rear row makes the retaining wall become more stable. Increasing the quantity of rows of retaining wall system can reduce the deformation and improve the stability of the double-pile-row retaining wall system. Increasing the length of piles of retaining wall system can reduce the deformation and improve the stability of the retaining wall system, and can also effectively increase the depth of excavation. When a self-supported soldier wall was selected to be the retaining system in sandy layer, the shape of the ground settlement induced by the excavation in this study was a triangular one. The affected area was 1.2 times the pile length behind the wall. According to this research, the multi-pile-row retaining wall system can be treated as a equivalent single row system, and a simplified stability analyzing method is fully adopted.