第五章 應用案例
6.2 建議
將未來可進一步探討之方向陳述於下以供參考：
26
1. 本研究僅探討降雨與河道水位變化對河岸穩定的影響，未來 可進一步考量河岸側向沖刷，期使模式更加符合現況。
2. 針對降雨所產生積水現象之簡易假設，未來可結合漫地流或 考慮蒸散作用之影響。
3. 未來可進行非均質土壤或具有層狀分佈之土壤，探討其特性 對河岸穩定之影響。
4. 本研究中假設河岸為土壤坡面，未來可考慮進一步結合植生 或其他保護工法之影響。
5. 破壞面假設為斜坡面，未來可考量為圓弧破壞面。
27
參考文獻
盧昭堯等，「921 地震後濁水溪下游輸砂關係之試驗研究(1/2)」，經濟部水利署水 利規劃試驗所，2006.
楊錦釧等，「砂質河川深槽變遷對河防建造物安全影響之分析(2/2)」，經濟部水利 署水利規劃試驗所，2009.
Bear, J. ,Dynamics of Fluids in Porous Media., Dover, Mineola, New York, 1972.
Chow, V. T., D. R. Maidment, and L. W. Mays, Applied hydrology, McGraw-Hill, 1988.
Chiang, S.W., Tasi, T.L., Yang, J.C., “Conjunction effect of stream water level and groundwater flow for riverbank stability analysis.” Environmental Earth Sciences, 2010.(accepted)
Collins and Znidarcic, “Stability analyses of rainfall induced landslides. ” Journal of Geotechnical and Geoenvironmental Engineering,Vol. 130(4), pp. 362-372, 2004.
Darby, S.E., Thorne, C.R., “Development and Testing of River-bank Stability Analysis.” Journal of Hydraulic Engineering, Vol. 122, No. 8, pp.443-454, 1996.
Dapporto, S., Rinaldi, M., Casagli, N., Vannocci, P., “Mechanisms of Riverbank Failure Along the Arno River, Central Italy.” Earth Surface Processes and Landforms, Vol. 28, pp.1303-1323, 2003.
Fletcher CAJ, Srinivas K, Computational techniques for fluid dynamics. 2nd ed., Springer-Verlag, Berlin ,New York,1999.
Fredlund, D.G., Morgenstern, N.R., Widger, R.A., “The Shear Strength of Unsaturated Soils.” Canadia Geotechnical Journal, Vol. 153, pp. 312-321, 1978.
Green, W. H., C. A. Ampt, “Studies on Soil Physics, 1. The flow of air and water through soils.”, Journal Agricultural Science ,Vol. 4, No. 1, 1911.
Harr M.E., Groundwater and seepage, McGraw-Hill, New York, 1962.
28
Horton, R. E., “The Role of Infiltration in the Hydrologic Cycle.”Transaction, American Geophysical Union, Vol. 14, pp.446-460,1933.
Huang, Y. H., “Stability Analysis of Earth Slopes.”Van Nostrand Reinhold, New York, N. Y., 1983.
HEC-RAS 4.1 River Analysis System User’s Mannual, Hydrologic Engineering Center, US Army Corps of Engineers.2010.
Iverson RM, “Landslide triggering by rain infiltration. ” Water Resources Research, Vol. 36, pp.1897-1910, 2000.
Lohnes, R., and Handy, R. L., “Slope Angles in Friable Loess.”Journal of Geology, Vol.76, pp.247-258, 1968.
Massimo Rinaldi, Nicola Casagli. “Stability of Streambanks Formed in Partially Saturated Soils and Effects Negative Pore Water Pressures: The Sieve River(Italy).” Geomorphology, Vol.26, pp.253-277, 1999.
Osman, A.M., Thorne, C.R.,“ Riverbank Stability Analysis: Part I. Theory.” Journal of the Hydraulics Division, Vol. 114, No. 2, pp.125-150, 1988.
Philip, J. R., “The Theory of Infiltration:1. The Infiltration Equation and its solution. ” Soil Science , Vol. 83, No.5, pp.345-357,1975.
Richard, L. A., “Capillary Conduction of Liquids Through Porous Mediums. ” Physics, Vol. 1, pp. 318-333, 1931.
Rawls, W. J., D. L. Brakensiek, N. Miller, “Green and Ampt Infiltration Parameters from Soils Data.” Journal of Hydraulic Engineering, Vol. 109, No.1, pp.62-70 ,1983.
Simon, A .,W. J., Molinas, A., “Mass-Wasting Algorithms in an Alluvial Channel Model.” Proceedings of the 5th Federal Interagency Sedimentation Conference, Las Vegas, Nevada, Vol. 2, No. 8, pp. 22-29, 1991.
Simon A, Curini A, Darby SE, “Langendoen EJBank and near-bank processes in an incised channel.” Geomorphology, Vol. 35(3-4), pp. 193-217, 2000.
Simon A, Thomas RE, Curini A, Shields FD, “Case study: Channel stability of the
29
Missouri River, eastern Montana.” Journal of Hydraulic Engineering , Vol.
128(10), pp. 880-890, 2002.
Spangler, M. G., Soil engineering (2d), New York, Internat. Textbook Co., pp. 483, 1960.
Thorne, C. R., Murphey, J. B., Little, W. C., “Bank Stability and Bank Material Properties in the Bluffline Streams of Northwest Mississippi.” Appendix D, Report to the Corp of Engineers Vicksburg District under, 1981.
Tsai, TL, “The influence of rainstorm pattern on shallow landslide, ” Environmental Geology, Vol. 53, pp.1563-1569,2008.
30
表3-1 Green-Ampt 降雨資料
Time(min) Rainfall Incremental
(cm)
Cumulative (cm)
Intensity (cm/hr)
0 0.0 1.08
10 0.18 0.18 1.26 20 0.21 0.39 1.56 30 0.26 0.65 1.92 40 0.32 0.97 2.22 50 0.37 1.34 2.58 60 0.43 1.77 3.84 70 0.64 2.41 6.84
80 1.14 3.55 19.08
90 3.18 6.73 9.90 100 1.65 8.38 4.86 110 0.81 9.19 3.12 120 0.52 9.71 2.52 130 0.42 10.13 2.16 140 0.36 10.49 1.68 150 0.28 10.77 1.44 160 0.24 11.01 1.14 170 0.19 11.20 1.02 180 0.17 11.37
(資料來源: Chow , Maidment, and Mays, 1988)
31
表3-2 Green-Ampt土壤入滲相關係數
Soil class 土壤分類
Wetting front soil suction head
ψ(cm)
Loamy sand 壤土質砂
Sandy loam 砂質壤土
Sandy clay loam 砂質黏土質壤土
Silty clay loam 沉泥黏土壤土
Sandy clay 砂質黏土
Silty clay 沉泥質黏土
(資料來源: Rawls﹐Brakensiek﹐and Miller﹐1983)
32
表4-1 模擬條件彙整表 探討條件
案例分析
降雨強度 (公厘/小時)
河道水位 速度改變 (公尺/小時)
降雨時間 (小時)
第一部分 (邊界固定)
5、10、20、
40、80、160 無 12
第二部分( 邊界改變
)
河道水位 上升段
5、10、20、
40、80、160 0.05、0.1、0.3 12
河道水位 下降段
5、10、20、
40、80、160 0.05、0.1、0.3 12
33
圖 1-1 評估河岸受沖刷後穩定性示意圖 (資料來源: Osman and Thorne ,1988)
圖1-2 評估河岸受地下水位與河道水位影響之穩定性示意圖 (資料來源：Darby and Thorne,1996)
34
圖 1-3 未飽和土壤莫爾-庫倫破壞準則 (資料來源: Fredlund and Rahardjo,1993 )
35
圖1-4 研究步驟流程圖
36
圖2-1 Green-Ampt理論之示意圖
圖2-2 Green-Ampt入滲模式示意圖
37
x h(x,t)
H1
h(x,t)
L
H2
圖2-3 一維Boussinesq方程式邊界示意圖
W S
P U
β
ψb
L Lsat
Luns
H
Hw
圖2-4 河岸穩定分析示意圖
38
(a)
(b)
(c)
圖3-1 Green-Ampt 降雨強度與入滲能力關係圖
39
在t=0,累積入滲深度F=0
時間 (min) Chow et al.(1988) 本研究
降雨量-Chow et al.(1988)
入滲量-Chow et al.(1988)
入滲量-本研究 降雨量-本研究
(b)
圖3-3 Green-Ampt計算驗證結果－(a)降雨組體圖與入滲率 (b)累積 降雨量與入滲量
41
42
(a)
x方向(m)
0 1000 2000 3000 4000 5000
水位(m)
0 1000 2000 3000 4000 5000
水位 (m)
43
Rinaldi and Casagli (1999)
(b)
Rinaldi and Casagli (1999)
圖3-5 安全係數驗證結果－(a)河道水位上升 (b) 河道水位下降
44
圖4-1 河岸穩定分析示意圖
(a)
46
(a)
(a)
5mm/hr 10mm/hr 20mm/hr
40mm/hr 80mm/hr 160mm/hr
(b) loam(c) Clay loam
48
49
50
(a)
52
53 Sandy loam (c) Clay loam
54
55
圖4-12 不同降雨強度於砂質壤土(Sandy loam)河岸穩定性之影響，
河道水位下降速度-(a) 0.05 m/hr (b) 0.1 m/hr (c) 0.3 m/hr
(a)
57
58
圖 5-1 濁水溪應用河段與西螺(2)雨量站位置圖
時間
2007/10/5 2007/10/7 2007/10/9
降雨強度(mm/hr)
0
20
40
60
80
入滲率(mm/hr)
0.0 2.0e-6 4.0e-6 6.0e-6 8.0e-6 1.0e-5 1.2e-5 1.4e-5 降雨量 (mm)
入滲率(mm/hr)
圖5-2 柯羅莎颱風降雨入滲率
59
斷面83左岸ٛ
0 500 1,000 1,500 2,000 2,500
高程(m)
圖 5-4 斷面 83 之 HEC-RAS演算最高安全係數水位結果
61
斷面71左岸
0 500 1,000 1,500 2,000 2,500
高程(m)
圖 5-6 斷面 71 之 HEC-RAS演算最高安全係數水位結果
63
斷面61左岸
0 500 1,000 1,500 2,000 2,500
高程(m)
(a)
(b)
圖5-8 斷面 61 之 HEC-RAS演算水位結果-(a)最高安全係數(b)安全 係數為1
65
斷面58右岸
0 500 1,000 1,500 2,000 2,500
高程(m)
67
(a)
(b)
圖5-10 斷面 58 之 HEC-RAS演算水位結果-(a)最高安全係數(b)安 全係數為1