坡地裂縫位置對邊坡穩定之影響

The Influence of the Slpoe Stability with Crack Position

林繼立(Chi-Li LIN)

指導教授 ： 張德鑫

中原大學/工學院/土木工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500521

摘要

未飽和裂縫邊坡土壤受降雨作用，除了部份降雨成為地表逕流外，其餘的雨水會隨裂縫滲入地表下，由於水之入滲除使地下水位升高外，亦使土壤中孔隙水壓力上生、增加土體下滑應力以及土壤抗剪強度降低之弱化現象，使得邊坡發生破裂變形，甚至發生滑動破壞。然而一般邊坡穩定分析常忽略裂縫、降雨滲流之影響，且大都將土體物理性質視為定值以分析其穩定性，並未考慮到裂縫、含水量變化對土體抗剪強度隨時間變化之影響，故其所評估之邊坡穩定性也未能顯示出於何時可能發生崩坍破壞，顯露出目前邊坡安全之分析尚不夠完備。
本研究結合降雨、滲流及邊坡穩定分析等知識與方法，及考慮不同深度與位置之坡地裂縫，應用地下水水流FEMWATER數值模擬模式，模擬有裂縫之邊坡在降雨後其土壤內含水量及地下水水位隨時間變化之情形，並將其含水量隨時間變化之結果轉換成STEDWIN邊坡穩定軟體所需物理參數，針對不同狀況，分析各時段之坡地安全係數，以推估邊坡之破壞時間與破壞面位置，探討降雨時坡地裂縫對邊坡穩定之影響行為。
模擬結果顯示，坡地安全係數值會隨裂縫位置改變而產生變化，坡地裂縫越深或越接近坡頂時越易發生破壞，而裂縫深度亦會造成邊坡破壞模式之改變。

關鍵字

坡地 ； 裂縫

並列摘要

When the soil with cracks in unsaturated slopes affected by rainfall, except that some rainfall becomes the surface runoff, other rainwater will be permeated with the crack under the surface. Because water infiltration besides making the water table rise, also increase the soil-water pressure, increase the glide stress of the soil, and decrease the anti-shear strength of soil, make slope becomes failure and deformation, even make it failure by slip. Generally the analyzed of slope steadily often neglects the influence of the crack, rainfall infiltration. We always let the soil body physical property as definite value in order to analyze its stability, and not considered that the change of crack, water content will influence the anti-shear strength of soil on time’s changing. So we can’t actually know when the collapse will happen by our slope stability analysis, so the analysis of slope depending yet not enough complete at present.
This research will combine the method of rainfall, infiltration and slope stability analysis, and consider the slope crack in different position , applies FEMWATER software in simulating the soil moisture content after a rainfall depending on time’s changing, and the increase and decrease of groundwater. Next, there are different soil parameters in different moisture content. Then, it applies the mode of STEDWIN software to count each stage the relations between safety factors of slope and time.
After the simulation test , we know that slope factor of safety will change which depends on the position of ceack. The failure will more easy happen when the slope crack in depth position or approaching the slope top, and the behavior of slope failure also will change with crack depth.

並列關鍵字

Crack Position ； the Slpoe

參考文獻

34.陳冠志、徐國錦(2003)，「坡地水流對崩塌影響之研究」，中華水土保持學報，34(1).pp.41-54。

54.郭麗娥(2003)，「未飽和紅土水力傳導係數之研究」，中原大學土木工程研究所碩士論文。

4.Bishop, A.W. (1955), “The Use of the Slip Circle in the Stability Analysis of Slopes”, Geotechnique, Vol.V, No.1, pp.7-17.

6.Morgenstern, N., and Price, V.E. (1965), “The Analysis of The Stability of General Slip surfaces”, Geotechnique, Vol.X V, No.1, pp.79-93.

7.Spencer, E. (1967), “A Method of Analysis of The Stability of Embankments Assuming Parallel Inter-Slice Forces”, Geotechnique, Vol.XⅦ, No.1, pp.11-26.