| Summary: | 碩士 === 國立成功大學 === 土木工程學系碩博士班 === 91 === Abstract
An elastic-plastic, dynamic three-dimensional (3-D) Finite Difference Method (FDM) is adopted to investigate the effects of granular pile improvement on dissipation of excess pore water pressure and mitigation of ground settlement during earthquake. To verify the appropriateness of dynamic model, undrained dynamic triaxial tests were simulated under different experiment conditions. The numerical predictions and laboratory measurement shows a similar tendency. Subsequently, a 3-D finite difference dynamic analysis was implemented on a sandy layer with and without granular pile treatment. The analysis was conducted incorporated with dynamic pore-water pressure calculation and fluid flow modeling. Numerical results with and without granular pile improvement were then compared to illustrate the improvement effect of granular pile on high liquefaction potential sandy stratum.
Eventually, a series of parametric studies were performed on installation parameters of granular pile includes pile configurations, pile permeability, pile diameter and pile length. The effect of various installation parameters were discussed in terms of dissipation of excess pore water pressure and reducing of ground settlement during earthquake. In this study, it was found that the improvement effect of granular pile on reducing the ground settlement may not be as beneficial as in the case of excess pore water pressure dissipation. The dissipation ratio of excess pore water pressure DR value varies from 9.16% to 88.5% for various improvement cases violently while the improvement ratio of ground settlement IR value alters mildly from 2.19% to 18.61%. This implies that the granular pile is predominantly capable of dissipating the induced excess pore water pressure to mitigate the liquefaction potential rather than reduce the ground settlement during the earthquake.
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