- 學位論文
礫石層對邊坡穩定影響之研究
A Study on Gravel Layer Influence Stability of Slope
摘要
邊坡由砂、土、礫石材料構成，各材料之岩性、粒徑分佈、級配、顆粒形狀等物理性質不同，對凝聚力、摩擦角等材料強度亦造成影響。每逢大雨過後，邊坡材料之含水量上升，造成黏土凝聚力下降、顆粒材料摩擦角降低，致使邊坡破壞事件頻傳。 現地高含水量之土壤材料強度量測不易，且前人研究常忽略礫石層對邊坡穩定性之影響，因此本研究以 SR5 應力控制流變儀量測不同含水量及砂土配比土壤之材料流變性質，並配合 Johnson 所提出之庫倫-黏滯係數模型推導出高含水量土壤之凝聚力與摩擦角。將推算結果所得之土壤強度參數代入 PFC 2D 離散元素法數值分析進行模擬試驗，模擬礫石表面摩擦係數不同與不同之礫石含量對材料強度之影響。模擬所獲得之材料強度，輸入PLAXIS有限元素法數值分析軟體型模擬分析，模擬不同礫石含量之礫石層及礫石層位置高度、厚度對邊坡穩定之影響，期望藉此研究對礫石層與邊坡穩定關係有進一步之瞭解。
關鍵字
庫倫-黏滯係數模型並列摘要
Slope were consist of sand, soil and gravel.Each composition with different lithologic characters, particle size distribution and particle shape would influence material strength such as cohesion and friction angle. After rainning, the water content of slope would increase and lead to cohesion and friction angle decrease, resulting in frequent slope destruction. It is hard to measurement the strength of high water content soil.Previous studies often ignore the influence of gravel layer to slope stability. Therefore, this study would designed with four steps to solve this question:Step 1: utilize SR5 program to measure rheological properties of material with different water content and different sand ratio. Step 2: utilize Coulomb-Viscous model to calculate cohesion and friction angle . Step 3:use PFC 2D program to simulation the relation to gravel content with strength of materials. Step 4: utilize PLAIXS program to simulation the relation to gravel layer with stability of slope.