本論文藉以岩體分類的觀點，探討非構造性控制破壞下岩坡之最陡安全開挖坡度。基於地質強度指標GSI，結合非線性之Hoek and Brown (2002)破壞準則以及線性之摩爾-庫倫破壞準則，以迴歸獲得不同坡高應力範圍下之岩體強度參數c'與 ；再利用Janbu邊坡穩定分析設計圖，反推不同坡高與不同岩體強度下，安全係數(FS)為1時的岩坡開挖坡度，並將其計算結果展繪為邊坡反應曲線Slope performance curve。 研究結果顯示：(1)不同坡高所造成之應力範圍，會直接影響岩體強度參數的評估，因此在評估岩坡穩定坡度時所使用之強度參數，應將坡高或應力條件納入考慮；(2)岩坡的岩石單壓強度，為非構造控制破壞之最陡安全開挖坡度中較為重要影響因素，相對而言，岩性係數顯得不那麼敏感；(3)岩坡之開挖施工擾動會直接影響岩體強度，尤其當岩體構造GSI評值不大時，岩體強度更會明顯降低；(4)依不同岩石強度與岩性展繪之GSI Slope performance curve可用來合理且簡易的評估岩坡最陡安全開挖坡度。 Stability of rock slope with non-structural control failures is studied in this thesis. Based on Non-linear Hoek-Brown failure criterion (2002), cohesion c' and frictional angle of the rock slope for different height (different stress range) are determined in conjunction with Geological Strength Index GSI. The maximum excavation angle (FS=1) with non-structural control failures of rock slope for different height can be evaluated using Janbu slope-stability chart. Consequently, GSI-based slope performance curves are constructed. The important results are summarized as follows: (1) Rock mass strength parameters are functions of stress range. Therefore, the height of rock slope should be taken into consideration for evaluating the maximum excavation angle. (2) Unconfined compressive strength of intact rock is a primary factor for evaluation of the maximum excavation angle with non-structural control failures. Relatively, the effect of material constant on the maximum excavation angle is minor. (3) Disturbance of excavation reduces the rock mass strength. The lower the GSI is the effect is more predominant. (4) GSI-based slope performance curves, taking the intact rock strength and material constants into consideration, are useful for evaluation the maximum excavation angle of rock slope.
