在擋土開挖的施工過程中，由於壁體產生變位將引起側向土壓力的解放，因而產生周圍地盤沉陷或側向變形，造成鄰近建物傾斜及管線損壞。因此，為了使工程師可提出更為有效且經濟的建物保護計畫，必須先行探討開挖所引致的地盤變位與壁體變形。 本研究利用離心模型試驗，探討於黏土層中以懸臂式擋土壁作為擋土設施並進行開挖，對壁體與鄰近地盤之影響；主要針對開挖深度、貫入深度及土壤強度等不同變數，進行懸臂式擋土壁開挖行為之相關研究與比較分析。 試驗結果顯示，黏土不排水剪力強度、開挖深度與貫入深度對地盤變位與壁體變形影響甚鉅。黏土層中懸臂式擋土壁開挖引致地表沉陷槽屬於三角槽型，沉陷影響範圍達5.2倍開挖深度之遠，並可利用樁頂水平變位求得壁後地表最大沉陷量，進而推估出壁後不同位置處之地表沉陷量。開挖引致壁體變形過程中，開挖面以下擋土壁有一固定不動點，隨著開挖深度增加，該不動點逐漸往下移動。樁頂至開挖面間的壁體承受正彎矩值，壁體正彎矩之最大值發生於開挖面處。 The lateral earth pressure will be released from the deformation of cantilever retaining wall during excavation. In consequence of the pressure decreasing, the surface settlement and lateral deformation may occur, and may endanger adjacent structures and lifelines nearby. Therefore, the movements of ground surface and the deformations of retaining wall induced by deep excavation must be studied, and then engineers can bring up an effective, economical and safety countermeasure for building protections. A series of centrifuge model tests were performed to assess the influence of depth of excavation and of penetration and of soil strength on the behavior of cantilever retaining wall standing in clay ground. From this study, it can be seen that the shear strength of clay soil, the depth of excavation, and the penetration depth influence the deformations of ground and the behavior of cantilever wall significantly. The shape of settlement trough induced by excavation is a spandrel type. The maximum surface settlement behind the wall can be found from the horizontal displacement of the top of the wall; and further, the surface settlement behind the wall with different distance from the wall can be predicted. There is a fixed point on the wall under the excavation level. The fixed point will move downward until the wall fails. The cantilever wall experiences the positive bending moment above the excavation level, and the maximum positive bending moment appears near the excavation level.
