| 摘要: | 台灣西部板岩帶的劈理位態大致呈東北-西南走向，向東南高角度
傾斜。高角度劈理在重力作用下會發生下坡潛變現象；在順向坡處發
生拱彎變形，此外也會發生漸進式的撓曲變形。當變形持續進行累積
時會使劈理角度改變且岩體風化破碎，在豪大雨期間可能會有滑動致
災之虞。板岩坡的調查研究在台灣已有多項計畫進行，累積了許多調
查報告與資料，可供進行控制因子分析，但對於影響變形速率的各項
因子尚未有深入的探討及分析。
本研究運用經濟部中央地質調查所多年期大型崩塌調查計畫及農
業委員會水土保持局大規模崩塌調查計畫中許多位於板岩坡的報告
與資料，整理出各鑽孔的滑動監測資料、岩心鑽探報告及水位監測資
料等，選取若干個不同因子進行研究。所採用的岩體類因子有：破碎
程度、風化程度、板岩占比、劈理傾角等。地下水類因子有：地下水
位深度、最大地下水位上升高度等。地形類因子有:孔口到坡腳高程差、
孔口到坡腳坡度。變形因子則包括：岩盤頂面變形速率、滑動面位移
速率。整理完各項因子資料後，先針對各個控制因子與各個變形因子
進行相關分析，挑選出相關性高的因子做為控制因子。最後運用多元
迴歸方法建立板岩重力變形的潛感模型，供台灣各板岩坡重力變形程
度之預估。
研究結果顯示岩體破碎程度、風化程度與坡度三項因子與岩盤頂
面變形速率呈現中度正向相關。劈理傾角離散程度與拱彎變形岩盤頂
面變形速率有中等正相關情形。若變形已產生滑動面，地下水因子(最
大地下水位上升高度與地下水位面到滑動面高程差)與滑動面位移速
率呈現高度正向相關。;The attitude of slaty cleavage of the western Taiwan slate belt is roughly in the strike of northeast-southwest dipping at a high angle to the southeast. It shows that high-angle cleavage is easily creeping downhill under the action of gravity. This includes buckling occurred at a dip-slope and also gradual flexuring deformation at the scarp slopes. When the deformation continues to accumulate, the cleavage dipping angle will change and the rock mass will become fractured and weathered. These may occur landslide disasters during heavy rains. Because the investigation of slate slopes has been carried out in many projects in Taiwan and many investigation reports and data have accumulated, these data can be used for controlling factor analysis, since it has not been discussed in-depth, especially at the analysis of various factors affecting the deformation rate.
This study used many reports and data of slate slopes from the multiyear large-scale investigation plan of the Central Geological Survey of the Department of Economic Affair and from the large-scale landslide investigation plan of the Water and Soil Conservation Bureau of the Council of Agriculture. I corrected deformation monitoring data of each
borehole, core drill logs, and water level monitoring data, etc., and also selected a number of different factors for research. The rock-mass factors used are: degree of fracturing, degree of weathering, slate contain ratio, cleavage dipping angle, etc.. The groundwater factors include: depth of groundwater table, maximum rise of groundwater table, etc. The terrain factors include: the height from borehole to the slope toe, and the slope angle from borehole to the slope toe. The deformation factors include: the deformation rate of the top of bedrock and the slip-rate of the sliding surface. After sorting out the data of various factors, first conduct correlation analysis for each factor and each deformation factor, and select the factors with high correlation as the control factor. Finally, a multivariate regression method is used to establish a susceptibility model for slate gravity deformation, which can be used to estimate the gravity deformation rate of Taiwan′s slate slopes.
The results show that factors of rock fracturing, weathering and slope angle are moderately and positively correlated with the deformation rate of the top of bedrock. There is a moderately positive correlation between the variance of cleavage dipping angle and the deformation rate of top of bedrock. If the deformation mass has developed a sliding surface, the groundwater factors, including the maximum groundwater level rise, and the height between the groundwater level and the sliding surface, is highly and positively correlated with the displacement rate of the sliding surface. |
