| Summary: | 博士 === 國立臺灣大學 === 土木工程學研究所 === 102 === This study explores the mechanism of the active lateral force in undrained clay when there is a spatial variability in the clay. It is shown that the effect of such spatial variability cannot be fully explained by the pure spatial averaging over a prescribed area or line; the tendency to seek the weak path for the critical slip curve is also important. Ignoring this important mechanism is risky, rendering the active lateral force estimate smaller than the actual value. Furthermore, pure spatial averaging cannot capture the phenomenon of the critical scale of fluctuation (critical SOF). However, it is found that the phenomenon of the critical SOF is connected to the nature of the spatial averages. The line averaging effect is significantly weaker than the area averaging effect, so the tendency for the critical slip curve to seek for a favorable location is stronger. Hence, the phenomenon of the critical SOF is more pronounced. It implies that if a strong pure spatial averaging is mistaken, the critical SOF can probably be ignored. This makes pure spatial averaging methods unconservative. Pure spatial averaging cannot capture this phenomenon of the critical SOF, because it cannot quantify the tendency of seeking the weak path. Therefore, the mechanism of seeking the weak path is explored in this study, and a probability distribution model for the active lateral force is proposed to characterize this sophisticated mechanism. Furthermore, a simplified procedure based on the distribution model is proposed to simulate the active lateral force samples without the use of the random finite element method or limit equilibrium method.
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