| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 105 === The waterfront retaining structures in coastal regions or port areas often extend below the surface of the water, where the sandy backfill materials are generally saturated. The variation of pore water pressure would have a great impact on the lateral pressure on the retaining wall. The rise of the dynamic lateral earth pressure and the water pressure may cause the deformation of the retaining structures during the earthquakes. However, in the previous studies, the effect of the change of pore water pressure on the lateral earth pressure was rarely discussed.
In this study, lateral earth pressure and pore water pressure were measured within saturated quartz sand subjected to vibration under the condition of no lateral displacement, i.e., under K_0 condition. The effect of vibration-induced water pressure generation on lateral earth pressure at rest in saturated sand was investigated to understand the interaction between sand particles and pore water during vibrations. Furthermore, the effect of aging on lateral earth pressure was also evaluated.
The experimental results show that the lateral earth pressure increases along with the water pressure generation simultaneously, so the effective lateral stress doesn’t change much at the beginning of vibration. This may be due to the effect of particle interlocking during pore water pressure changes. With the vertical effective stress decreasing due to the water pressure increase, K_0 would increase up to more than 1.0. Because of particle interlocking, the lateral earth pressure would rise and may exceed the vertical earth pressure. In addition, K_0 increases from about 0.4 to 0.5-0.7 during the 24 and 48 hours periods after the completion of the specimen preparation. The effect of particle interlocking is evaluated based on the results of the pore pressure ratio r_u, the water pressure increment u_e, the coefficient of lateral earth pressure at rest K_0 and the lateral earth pressure σ_h at the starting point of losing particle interlocking for a better understanding of the mechanism of particle interlocking.
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