| Summary: | 碩士 === 國立中興大學 === 水土保持學系所 === 100 === Firstly, this study performed a three-dimensional (3-D) finite element numerical analysis on a retaining piles stabilized slope at Ali-Shan Wu-Wantzy landslides (or Ali-Shan landslides) to inspect the slope stability and in-situ lateral earth pressure acting on piles. Subsequently, the lateral earth pressure of simulation was compared with that of measurement to verify the validities of the numerical procedures and input material model parameters. Meanwhile, two groups of fictitious model slope, namely, colluvium slope (homogeneous slope) and colluvium-bedrock slope (heterogeneous slope) were set up for a series of numerical experiments on the design parameters of retaining pile. In the numerical experiments, the slope inclination angle (β), unit weight of colluvium (γunsat, γsat), location of retaining pile (Lx/L), spacing ratio of retaining pile (S/D) and length of retaining pile (Lp) were selected as numerical variables to inspect their influences on the slope stability and the mechanical behaviors of retaining piles.
For the simulation of the retaining piles stabilized slope at Ali-Shan landslides, it was shown that the lateral earth pressure of simulation is excellent in agreement with that of measurement. Moreover, the numerical experiments of retaining pile in homogeneous slope reveal that in the case of β=25˚ (mild slope), the potential sliding surface mobilizes at the up slope of the retaining piles if the piles are installed adjacent to the slope toe. Nevertheless, the potential sliding surface turns into mobilizing at the down slope of the retaining piles as the piles are gradually moving toward the up slope. On the contrary, in the case of β=45˚ (steep slope), the potential sliding surface mostly mobilizes at the up slope of the retaining piles. In addition, in the case of β=25˚~45˚ (slope inclination angle of wide range, mild slope ~ steep slope), the factor safety FSp of the slope stabilized by retaining piles are insensitive to pile length Lp if the piles are installed nearby the slope top or slope toe. On the contrary, the pile length Lp becomes influential to the factor safety FSp if the retaining piles are installed adjacent to the central area of the slope.
Finally, the numerical experiments of retaining pile in heterogeneous slope demonstrate that in the case of β=35˚ (medium slope) and the bedrock penetration ratio of retaining pile Rr (=Lpr/Lpa，where Lpr and Lpa are the bedrock penetration depth and colluvium penetration depth of retaining pile respectively)=3, the factor safety FSp of the slope approximates a maximum value (FSp)max and the value gradually descents with the increasing installation spacing ratio (S/D) of retaining pile. In the stability analysis of strength reduction method (SRM), the factor safety of slope FSp is not influenced by the bedrock penetration depth once the retaining pile penetrates through the colluvium into the bedrock. In the case of β=25˚ (mild slope), the maximum bending moment of retaining pile is not influenced by the bedrock penetration depth and approximates a constant when the bedrock penetration ratio of retaining pile Rr greater than 2 (Rr>2). On the contrary, in the case of β =45˚ (steep slope), the maximum bending moment of retaining pile increases with the increasing bedrock penetration ratio Rr and this indicates the mobilization of maximum bending moment of retaining pile in steep slope is greatly influenced by the bedrock penetration depth.
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