水份是土石流運動的重要因素之一。本研究在窄渠道內進行顆粒流崩塌實驗， 並分析其流動物理特性及機制，為彌補實驗無法了解顆粒流內部力量傳遞過 程，使用PFC-3D數值模擬與實驗比較，實驗部分主要分成乾顆粒崩塌、濕 顆粒崩塌、水下顆粒崩塌並以細磨石為實驗材料，數值模擬部分則以聚苯乙 烯顆粒為實驗材料，並在底部黏上顆粒定床，而堆積塊體高寬比a作為主要對比參數。 本研究在堆積塊體崩塌顆粒流運動過程中，主要分析堆積型態、壓力變 化、速度變化，在PFC-3D數值模擬部分主要觀察其內部接觸力、不平衡力、 動能、摩擦損耗之變化，並與實驗組做對照，其分析也是以堆積型態、壓力 變化、速度變化為主，結果顯示顆粒流在水下運動過程中受黏滯性影響速度 較慢，但受顆粒與水流體化效應導致堆積距離稍遠，內部壓力變化在崩塌時 側端壓力計產生負壓，顆粒流運動造成前端壓力計產生正壓，在PFC-3D數 值模擬中與實驗組比較發現整體物理流動行為是相近的，在較大的高寬比a 產生較大動能，能量損耗也較多，但數值模擬能量消散較快，導致堆積距離 較短且最大流動層厚度較小。 Both Flume experiments and numerical simulations (PFC-3D) were employed to examine the granular collapses of ballistic mill stones under wet (submerged) and dry conditions. The flow characteristics and pore water pressure variation during the collapse of particle piles are experimentally analyzed by flow visualization and pressure sensors. The effect of aspect ratios of the granular piles under submerged and dry conditions is also examined by measuring the dynamic pore water pressure and the flow characteristics. The variation of pore water pressure is associated with the particle collapse patterns. Negative water pressure occurs as the region of submerged pile is in dilation (upper part), while the positive water pressure is induced at the front bottom by particle impingement. The results of PFC-3D simulations for the dry granular flows are generally in agreement with experimental results, but with shorter run-out distances and smaller mobilized thickness.
