| 摘要: | 台灣地形陡峻、兩量豐沛，急流易造成河床沖刷，破壞構造物，溪流整治成為防災最重要工作。石梁固床工因取材容易且符合生態景觀、材質自然化、施工經濟化等原則，為最常見的保護河床橫式構造物之一，惟對石梁固床工整體排列的力學穩定性分析之理論尚待開發。本研究以DDA(Discontinuous Deformation Analysis)分析法建立一套分析模式了解石梁固床工在不同排列型式對河床穩定性之影響。
本研究首先就國內外野溪整治固床工之水理分析與排列模式作回顧，作為選定石材尺寸、排列模式，並以常流水之溪流為主要模擬對象，考慮在6m、10m、兩種河床寬度，運用八字型排列、拋物線型排列、均勻顆粒排列等三種排列法在不同拱高比(1/3、1/4、1/6、1/8)排列組合，應用DDA分析法尋找出在不同的流速下最適合的排列模式。
本研究分析成果顯示拱高比比例的差別可明顯影響其穩定性，而在各排列模式當中拱高比1/8比拱高比1/3平均位移量多出390%~726%。而不同的在三種排列模式當中，八字形排列比其他兩種排列模式更能承受較大流速之衝擊。
Taiwan have high and precipitous landform with plentiful rainfall, a high speed flow stream easily to cause a riverbed scrub and destroy structures, so to dredge stream become the most important work of preparedness against natural disaster.
Stone sill is the most common protection river bed scouring structures on the transverse direction of rivers, due to some principles of easy to get material and tally with ecological landscape, material naturalized and the economically construction, only the analysis theory of stone sill entirety permutation in stability still need to be developed. In this study, we use the DDA (Discontinuous Deformation Analysis) method to build an analysis model, so that can understand the different permutation style of stone sill to the influenced of riverbeds’ stability.
First, this study will review the solid-bed hydraulic engineering analysis and alignment model of abroad and internal wild stream, to be a mold of selection the stone size, permutation pattern, and as the main simulation object of the usually stream, to consider for two riverbed’s width of 6m and 10m, Use the three permutation methods: 8 word-type array, parabolic and uniform arrangement, even particle permutation in different rise-span ratio (1 / 3, 1 / 4, 1 / 6, 1 / 8) permutations and combinations, application DDA to find out the most suitable permutation under a different flow speed mode.
The analysis result of this study showed differences in the proportion of rise-span ratio can significantly influence the stability, of the mode in every permutation shows the average displacement of 1/8 rise-span ratio will increase 390% ~ 726% than the 1/3 rise-span ratio. And in the different three permutation models, the 8 word-type array can sustain higher flow speed attack than other two models. |
