| 摘要: | 各地山區經常因為地形坡度、土石量的大小及多寡、豪雨等引發坡地災害，若是土石顆粒於發生崩塌流動的同時，又侵蝕和夾帶底床的土石，則會造成更大規模的崩塌災害，導致附近居民生命安全危害與財產損失慘重，因此本研究將利用實驗模型來了解崩塌流動過程的現象。
本研究主要以實驗方式探討不同崩塌床顆粒尺寸與不同崩塌床初始寬高比對於不同可侵蝕床顆粒尺寸的侵蝕與堆積影響。實驗設備將使用一開放式二維傾斜流槽裝置，以手動快速拉起擋板使崩塌床顆粒釋放至可侵蝕床中，同時以電子天平稱量流出流槽之顆粒。實驗顆粒以黑白兩色顆粒區分，並利用影像處理方法來分析崩塌床與可侵蝕床的流場變化、崩塌床區剩餘面積、流動距離、流體深度隨著時間與距離的關係以及可侵蝕床的侵蝕面積隨時間的關係、最終侵蝕面積隨位置與寬高比的關係、流槽中各位置上的侵蝕面積隨著時間的變化、侵蝕速率的比較。
由實驗結果得知，顆粒尺寸與崩塌床寬高比皆會對崩塌床顆粒與可侵蝕床顆粒的流動行為有一定的影響。當可侵蝕床顆粒尺寸為大顆粒時，流出質量會較小而崩塌床的量化結果則會較大，是由於小顆粒於流動過程中會進入大顆粒與大顆粒之間的空隙，使小顆粒的流動受到阻擋，進而持續向上堆積使崩塌床顆粒流體深度較高、殘留面積變大。而當可侵蝕床顆粒尺寸相同時，侵蝕面積會隨著崩塌床顆粒尺寸越大而越大。在改變不同崩塌床初始寬高比的過程中，不論是流出質量還是影像分析量化的結果都會隨著崩塌床初始寬高比的增加而變大，單位時間內的變化率也是變大的。此外，我們在這也探討隨著時間的經過及在流槽中的不同位置上，崩塌床顆粒與可侵蝕床顆粒的流場變化與流動趨勢。最後，崩塌床的位能能量損失率對於不同可侵蝕床顆粒尺寸的侵蝕面積會有不一樣的影響，主要是因為造成能量損失的原因與分布不同有關。
;Mountains in various regions often cause slope disaster due to terrain slope, the size and amount of soil and rock and heavy rain, etc. If the particles are eroding and entraining the soil and rock in the bottom bed at the same time as the flowing after collapse, it will cause a massive avalanche. Resulting in the human life safety hazards and the heavy property losses from residents. Therefore, the experimental model can be used to understand the phenomenon in the process of the avalanche flow in this study.
This study mainly uses experimental method to explore the effects of the different particle sizes of the granular bed (including the column bed and erodible bed) and the initial aspect ratio on the erosion and deposition behavior in the avalanche granular flow field. The experiment used an open two-dimensional inclined channel. We pulled up the baffle quickly by manual to release the particle from the column bed and measure the accumulated mass out with an electronic balance simultaneously. The experimental particle colors are distinguished by black and white, which can be analyze by image processing method. The flow field of the column bed and erodible bed, mass flow rate, residual area, runout distance, flow depth of the column bed, erosion area, final erosion area and erosion rate will be analyze and discuss in this research.
From the experimental results, it can be known that the particle size and the initial aspect ratio both have significant influence on the flow behavior of the column bed and erodible bed. When the particle size of the erodible bed is large, the accumulated mass out will be smaller and the quality of column bed will become larger. Because of the small particle enter in the gap between particles, the flow of small particle is blocked and then continued to accumulate upwards so that the flow depth of the column bed will be higher. However, when the particle size of the erodible bed is the same, the erosion area increases with the particle size of the column bed increases. In the process of changing the initial aspect ratio, the mass flow rate increases with the aspect ratio increases. Moreover, we also analyze and investigate the variety of the flow field and the flow trend of the column bed and erodible bed particles along the time and at different positions. Finally, the potential energy loss rate of the column bed has different effects on the erosion area of different erodible bed particle sizes. This is related to the different of the reason and the range for the energy loss. |
