本研究分別於苗栗縣火炎山一號坑中進行土石流現地監測，以及於國立中央大學大型力學實驗館進行逕流引致土石流之顆粒實驗分析。前者透過攝影機影像資料記錄土石流事件之流動歷程，估算礫石型土石流前端部平均速度介於0.4 m/s-1.1 m/s。彙整2016年到2021年間所發生土石流之降雨資料，並歸納出有效累積雨量(前期降雨) (R)與雨場累積雨量(Re)二種參數分別與土石流流動距離(L)皆具有正相關趨勢。三維地聲儀所記錄之地聲訊號，顯示逕流事件頻率範圍為20到90 Hz之間；高含砂水流事件頻率範圍為30到80 Hz之間；地震事件頻率範圍為5 Hz以下。後者顆粒堆積底床之實驗，探討顆粒之流動型態與破壞歷程、顆粒流運動特性、逕流破壞後之堆積體參數以及與水流功率之相關性。供水量與水槽傾斜坡度條件之不同，會造成不同的流動型態。當顆粒堆積底床受到逕流破壞時，隨著坡度與流量條件之增加，即水流功率增加，使水流沖蝕顆粒堆積底床的能力更強、捲增效應更加顯著，讓顆粒流波峰高度於流動過程中呈現遞增之趨勢。;In this study, we conducted field surveys of debris flows at the Houyenshan of San Yi county, Miaoli, Taiwan, and conducted particle experiments analysis of runoff-induced debris flows in the large-scale mechanics laboratory of National Central University. The former recorded the flow progress of the debris flow events through image data filmed by cameras, and found that the average velocities at the front of the debris flows were between 0.4 m/s-1.1 m/s. We collected the rainfall data of the debris flows occurred from 2016 to 2021, and concluded that the effective accumulated rainfall (including antecedent rainfall) (R) and the accumulated rainfall (Re) of the rain field have a positive correlation with the flow distance (L) of the debris flows. The signals recorded by the three-dimensional geophones showed that the frequency range of runoff events are between 20 and 90 Hz; the frequency range of debris flood events are between 30 and 80 Hz; the frequency range of earthquake events are below 5 Hz. The latter experiments of loose bed explores the granular flow pattern and failure processes, granular flow motion characteristics, accumulation parameters after runoff failures, and the correlations with stream power. The differences between the slope and the discharge conditions of the experimental tilting flume will cause different flow patterns. When the loose bed is fluidized by runoff, the ability of water flow to entrain the loose bed will be stronger as the slope and the discharge increase. The surge of the granular flow shows an increasing trend during the flow process.
