研究期間：10101~10112;CENTRIFUGE MODELLING AND NUMERICAL SIMULATION ON SEISMIC SLOPE STABILITY OF A COHESIVE EMBANKMENT The main objective of the present study is to evaluate the yield acceleration and seismic residual deformation of a given slope made of clay. Yield acceleration is defined as the minimum pseudo-static acceleration required to produce a significant deformation of a slope. Seismic residual deformation is an index to represent the degree of embankment instability caused by seismic loading. This project plans to perform centrifuge modelling to study the yield acceleration and seismic residual deformation of a cohesive slope when subject to earthquake loading using the dynamic centrifuge. Different cohesive slope model will be prepared with clayey soils of different consistency. A number of real earthquake acceleration histories will be selected to be the input motions to shake the model slope. Dynamic responses of model slope will be monitored by arrays of accelerometers, piezometers, and LVDTs. Test procedure will be arranged to increase peak acceleration step by step to find out a minimum value beyond which the slope starts to deform significantly. The minimum value can be defined as yield acceleration. The deformation pattern and failure surface will be recorded by mesh mark. It is expected that the consistency of clayey soil plays an important role in slope stability. The dynamic stability also depends upon the earthquake intensity and duration. The intensity can be represented by a peak acceleration and the duration is denoted by an equivalent loading cycle. Thus an experimental relationship among permanent displacement, yield acceleration, consistency of clayey soil, slope geometry and earthquake loading is expected to be obtained from the limited test results. This project also plans to conduct numerical modelling to implement experimental approach. Two kinds of numerical approach will be adopted to model the dynamic response of a cohesive embankment. One is using finite difference software FLAC2D and the other is the Newmark‘s approach combined with a slope stability analysis method of slices, such as Bishop’s simplified method. These two numerical methods will be calibrated and verified with the results of dynamic centrifuge test and earthquake cases of India and Taiwan. After calibration, a great number of numerical tests will be performed to establish the relationships among permanent displacement, yield acceleration, consistency of clayey soil, slope geometry and earthquake loading. These relationships will be refined and simplified into simple design charts and tables so that the research results can be utilized in engineering practice.
