| Summary: | 碩士 === 國立嘉義大學 === 土木與水資源工程學系研究所 === 94 === Except the geometry of slope, the geometric type of rockfall is major factor influencing motion behavior of rockfall. Two dimensional disc or three dimensional sphere were mostly used to numerically simulate rockfall motion. But circle or sphere could not represent the real geometry of rockfall. Thus, in this study an Eccentric Circle Model was specifically proposed to estimate motion behavior of non-circular rockfall. Furthermore, three kinds of rockfall model including circle, ellipse and eccentric circle, were simulated to fall through four kinds of slope shape and impact defense wall for subsequent analysis and comparison.
The results of simulation revealed that eccentricity value 0.5 of Eccentric Circle Model was the critical value of rebound height on the simple slope. As eccentricity value was small, the characteristic of motion was close to ellipse which was easily to rebound. On the contrary as eccentricity value was large, the characteristic of motion was close to flat piece which was more stable and was easier to slide.
When rockfall impacts defense wall, the rockfall of circle model holds higher force and energy value and tends to be conservative. But there were exceptions on the slope of high angle. The rebounded height of circle model is just between ellipse and eccentric circle models and is not conservative.
As concluded, three kinds of rockfall models were used to numerically simulate non-circular rockfall experiment cases and for comparison of the results of experiment. The simulation of Eccentric Circle Model could approach the non-circular experiment trajectory and energy loss. Thus, the Eccentric Circle Model could be effective in estimation non-circular rockfall motion behavior.
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