國內外軟弱地盤之深開挖，大都採用擋土壁作為擋土結構，但是周圍地盤會因開挖作業的進行而產生沉陷或側向變形，造成鄰近建物傾斜及管線損壞。 本研究首先進行試體準備工作，為了模擬現地土壤性質，使用水力坡降壓密的方法製作沿深度增加，其強度隨之增加的紅土試體。然後利用縮尺之模型擋土壁進行離心模型試驗，來模擬現地擋土壁的尺寸，探討懸臂式擋土壁開挖過程時壁體彎矩分佈，地表沉陷，壁體變位等行為。 試驗結果顯示，土壤強度與壁體傾斜量有著 的關係，擋土系統破壞時壁體之彎矩及壁後地表沉陷快速變化與增加，且地表最大沉陷量與壁體前傾量亦有著 的關係。 Deep excavation is frequently adopted in the construction of buildings in urban areas. However, the surface settlement and the lateral deformation induced by deep excavation may endanger the adjacent structures and cause the damage of nearby lifelines as well. In this study, the clay bed with the shear strength increasing with depth was first prepared by the hydraulic gradient consolidation technique. A series of model tests was then conducted in the centrifuge to simulate the excavation of a cantilever retaining wall in soft clay. The bending moment on the wall and lateral displacement of the wall, the surface settlement, and the heaving deformation induced by excavation were measured continuously. From test results, the soil stability number(m) and the lateral displacement (δc) of the wall is related as . The bending moment on the wall and the surface settlement increase dramatically when the retaining wall collapsed. The relationship of the maximum lateral displacement of the wall and the maximum surface settlement is proposed as .