斷層一旦發生錯動，強烈的地震波和地表永久變形，常讓鄰近斷層帶的結構物造成嚴重變形而導致破壞。但臺灣地狹人稠且維生線系統分佈範圍廣大，很難將所有結構物全面避開斷層帶。因此暸解斷層錯動的影響範圍及近地表變形之特性，是值得受到重視和研究的課題。 本研究利用離心模型試驗模擬正斷層與逆斷層錯動方式，以瞭解正斷層及逆斷層通過黏土層之影響範圍及變形特性。試驗土樣採用甘油與皂土混合而成的人工黏土，在試驗過程中甘油不易排出，極適合模擬斷層快速錯動時，地盤屬於不排水受剪的情形。 試驗結果顯示，正斷層引致的地表裂縫範圍隨著覆土層厚度增加而增加。但在相同的覆土層厚度條件下，正斷層引致的地表裂縫範圍，隨著覆土層的不排水剪力強度增加而減少。不論是覆土層經正斷層或逆斷層錯動後，在相同的覆土層厚度下，其地表陷落或抬昇範圍都與覆土層的不排水剪力強度呈負相關。由於複合土層為砂土層覆蓋黏土層，經斷層錯動後，近地表變形與純砂土層之變形相近。但複合土層在砂土與黏土的界面，黏土表面會產生階梯狀的變形。 Strong seismic waves and permanent ground deformations induced by fault slip would lead to the serious damage of structures near the fault zone. It is very difficult to avoid the fault zone for the residential area and the lifeline systems, especially in Taiwan with high density of population. Therefore, it is an important issue to realize the influenced zone and the characteristics of ground deformation by fault slip. In this study, a series of centrifuge modeling tests were conducted to simulate the normal and reverse faulting through clay layers and sand overlying on the clay to observe the influenced zone and characteristics of ground deformation. An artificial clay, Glyben, mixed with bentonite and glycerin was used as test soil. The Glyben is applicable to simulate the undrained condition of soil layer under the rapidly shear by fault slip because the glycerin was difficult to drain out during shearing. According to the test results of normal fault, the range of surface cracks increases with the increasing thickness of overburden soil layer. With the same thickness of overburden soil layer, the range of surface cracks decreases with the increasing undrained shear strength of soil. For either the normal fault or the reverse fault, the ground surface deformation is negative proportional to the undrained shear strength of soil. However, the ground surface deformation of muti-layer soil, which consists of a clay soil at the bottom and a sand soil above, is close to that of sandy soil, and a step-shape deformation occurred at the interface of the sandy and clay layers.
