由臨界楔形體模型可得楔形體及其基底滑脫面之強度與楔形體形貌之關聯性，根據臨界楔之臨界角，即可反衍楔形體與基底滑脫面之強度參數。本研究將非線性Hoek and Brown破壞準則引入臨界楔模型中，使楔形體強度遵守非線性準則，因此，臨界角將隨楔形體厚度變化而變化。研究結果發現，楔形體強度隨楔形體厚度增加而下降，且臨界角將隨之增大，但增加幅度將隨厚度增加逐漸趨緩。本研究藉由台灣三個褶皺逆衝帶剖面進行模型驗證，經由輸入合理參數值以及計算所得之臨界角，結果顯示模型計算與剖面觀察相符。利用參數敏感性分析得知，強度參數中以地質強度指標、基底滑脫面摩擦係數與基底滑脫面孔隙水壓比對本模型之影響程度較明顯。研究結果顯示，本文建議的非線性Hoek and Brown破壞準則之臨界楔模型，除了可考慮臨界楔厚度影響之外，亦可根據野外調查所得之岩體強度指標，合理的推估楔形體之強度，免除原臨界楔模型決定岩體抗剪摩擦角之困擾。 This study incorporates the nonlinear Hoek and Brown failure criterion into the critical taper model to evaluate the variation of the taper angle of thrust belt with changes of wedge thickness. From collected wedge profile found wedge geometry about three types of morphology were fixed angle, convex upward and concave upward. Because the lateral pore pressure changes at the wedge and the detachment, and formation strength (GSI) change at the wedge, as well as effect of non-linear wedge strength. The wedge strength will decrease with the increasing of wedge thickness. Accordingly, the taper angle increases with the increasing of wedge thickness. Based on the parameter study, the basal coefficient of friction, the basal Hubbert-Rubey pore-fluid pressure ratio on the detachment fault and the Geological Strength Index of the wedge dominate the relation between wedge thickness and taper angle. Therefore, the nonlinearity of wedge strength should be considered for evaluating the mechanical characteristics of thrust belt wedge.
