大型的岩石崩滑(Rock Avalanche)挾帶著大量的土石及驚人的速度，移動至極遠的距離，進而引發生命、財產極大的損失。因此，大型岩崩的崩塌潛勢以及崩塌後之影響範圍，均應進行系統性之探討。 本研究利用極限平衡分析法，計算於安全係數為1時不同坡高之均質有限岩坡發生大型岩崩之臨界坡度，並根據分析結果建立GSI-Based 邊坡反應曲線數學式，同時，利用迴歸以及非線性最佳化法，建議已知岩性、岩體結構、岩石強度和岩坡高度下之岩坡臨界坡度，方程式進一步配合岩坡現地坡度，以做為大型岩崩的崩塌潛感指標，並藉以評估大型岩崩之崩塌潛勢。其次，本研究利用岩坡極限平衡分析之滑弧幾何，據此推估大型岩崩之崩滑體積，並透過經驗式建立崩塌體積及崩塌影響範圍之關係。經統計不同岩性、岩體結構、岩石強度和岩坡高度之推估崩滑體積，發現崩滑體積量為岩坡的坡高與臨界坡度的函數，並據以建立大型岩崩體積估計之方程式。最後，本研究將大型岩崩之崩塌影響範圍區分為崖頂影響區和坡趾影響區。經統計後發現崖頂影響區為坡高的1/5~2/5倍，坡趾影響區則亦為坡高及臨界坡度之函數。本研究結果可提供做為不同地質條件大型岩崩潛勢分析以及崩滑影響範圍評估之參考。 “Rock Avalanche” with long runout distance frequently bring out great loss of life and property. Consequently, evaluations of the susceptibility of rock avalanche and its influence zone are important. In this study, the stable angle (FS=1) of non-structural control failures using Bishop’s method was evaluated. Using nonlinear regression and optimization method, equations which can be plot as GSI-based slope performance curves were proposed. The proposed equations can be used to estimate the stable angle of rock slope with known material constants (mi), intact rock strength(σci), geological strength index(GSI) and slope height. The ratio of the slope angle and calculated stable angle can be used as the rock avalanche susceptibility-index. Besides, this study estimated the mass movement volume of a rock avalanche according to the results of slope stability analysis. The runout distance of rock avalanche can be estimated using a empirical relation of slid mass volume and runout distance. Base on the statistics analysis, this study proposed equations for estimating the runout distance with known slope angle and slope height. Finally, the influence zone, including upslope and downslope, of rock avalanche has been proposed. The proposed influence zone of rock avalanche are function of slope angle and slope height.
