臺灣博碩士論文加值系統

傳統土壤力學的研究領域，通常專注在飽和土壤的行為上。飽和土壤力學缺乏對於不飽和土壤行為機制的了解及關於氣候變動因素影響地下水文狀態邊界模式評估的兩個主要缺點。然而許多工程實務問題是屬於不飽和土壤的問題，本研究的目的即在應用不飽和土壤力學理論與試驗，針對不飽和邊坡因降雨導致破壞的原因與機制進行探討研究，以提供日後對類似邊坡進行保護工作時的參考。
本研究已研製出一套不飽和土壤三軸試驗儀器，可進行一系列不飽和土壤剪力強度試驗之研究。本研究根據不飽和土壤邊坡之特性，針對林口紅土台地之分析結果顯示：在平時，由於土體中存在之基質吸力，造成土壤剪力強度提高而使邊坡處於穩定狀態，但當暴雨來臨時，降雨入滲在邊坡表面形成之浸潤帶，將會使得邊坡因基質吸力的下降，而導致邊坡於浸潤帶內發生淺層近似平面的破壞面。
研究結果顯示對於凝聚性不飽和土壤邊坡之保護，坡面之防水措施可能比排水重要。因為當暴雨入滲至邊坡中，將會先飽和土體使其強度軟化，造成土壤中基質吸力之下降而使邊坡處於不穩定之狀態。適當的坡面植生為可行的防治方法之一。

Classic soil mechanics has focused on the behavior of saturated soils. The shortcomings associated with classical soil mechanics are the lack of consideration of the behavior of unsaturated soils and the missing of a model for the moisture flux boundary condition imposed by climate conditions. However, many geotechnical problems involve unsaturated soils above the groundwater table. The objective of this research is to apply the principle of the unsaturated soil mechanics to study the rain-induced slope stability of unsaturated soil slope.
This study has developed a set of the unsaturated soil triaxial apparatus which can conduct a series of the shear strength test of unsaturated soils. Considering the characteristics of unsaturated soils, slope stability analyses were carried out for the Linkou lateritic terrace. The results are as follows:（1）matric suction increases the shear strength of unsaturated soils and thus increase the factory of safety of the slope stability in the dry season; （2） rain infiltration results in the forming of a wetting band and reduction of matric suction, consequently, decreases the apparent cohesion of the unsaturated soil. Then, a shallow-type of failure would take place within the wetting zone.
This study shows that slope surface protection that can prevent rain infiltrating is more effective than the horizontal drains for the unsaturated soil slope. Rain infiltration may saturate soil and decrease the apparent cohesion of unsaturated soil. Consequently, the slope may become unsable. The most effective way to prevent failure of unsaturated soil slope appears to be to protect the slope surface from excessive rain infiltration.

摘要I
ABSTRACTII
誌謝III
目錄V
表目錄VII
圖目錄VIII
第一章　緒論1
1.1　研究動機與目的1
1.2　研究方法與內容2
第二章　文獻回顧4
2.1　不飽和土壤之微觀特性
2.1.1　飽和及不飽和土壤之組成4
2.1.2　土壤總吸力（Total Suction）6
2.1.3　基質吸力（Matric Suction）8
2.1.4　土壤水份特性曲線（Soil-Water Characteristic Curve）11
2.2　不飽和土壤應力狀態14
2.3　不飽和土壤的剪力強度定理17
2.3.1　飽和土壤破壞理論17
2.3.2　不飽和土壤破壞理論18
2.4　不飽和土壤邊坡之穩定性分析21
2.4.1　殘積土坡21
2.4.2　雨水入滲行為22
2.4.3　降雨引致邊坡坍方之機制25
2.4.4　坍方機制的實驗室模擬方法26
2.4.5　不飽和土壤邊坡之穩定性分析27
第三章　不飽和土壤三軸試驗儀之研製、校正及試驗方法32
3.1　不飽和三軸試驗儀器之研製32
3.1.1　孔隙水壓力的控制和量測33
3.1.2　其他壓力及體積的控制系統42
3.1.3　擴散空氣體積指示器45
3.1.4　控制面板及試驗設備49
3.2　試驗儀器校正53
3.3　試驗步驟53
3.4　基本物理性質試驗結果62
第四章　不飽和土壤邊坡穩定分析63
4.1　不飽和土壤邊坡穩定性分析模式之建立63
4.2　分析參數之求取65
4.3　分析結果82
4.4　坍方防治方法之建議96
第五章　結論與建議100
5.1 結論100
5.2 建議101
參考文獻102
符號說明106

[1] Fredlund, D. G., "An Introducting to Unsaturatrd Soil Mechanics," Unsaturated Soil Engineering Practice, ASCE, pp.1-37 (1997).
[2] Fredlund, D. G., and Morgenstern, N. R., "Stress State Variables for Unsaturated Soils,"Journal of Geotechnical Engineering, ASCE, GT5, vol.103, pp. 447-446 (1977).
[3] Bear, J., Hydraulics of Groundwater, McGraw-Hill, USA (1979)
[4] Lambe, T. W., "The Engineering Behavior of Compacted Clay,"Journal of Soil Mechanics amd Foundation Division, ASCE, Vol. 84, SM2, Paper no. 1655, pp. 1-35 (1958).
[5] Croney, D., and Coleman, J. D.,"Soil Thermodynamics Applied to the 7Movement of Moisture in Road Foundations,"Proc. 7th Int. Cong. Appl. Mech.,Vol. 3, pp. 163-177 (1948).
[6] Edlefsen, N. E., and Anderson, A. B. C.,"Thermodynamics of Soil Moisture,"Hilgardia, Vol. 15, pp. 31-298 (1943).
[7] Richard, B. G.,"Measurement of the Free Energy of Soil Moisture by the Psychrometric Technique Using Thermistors,"in Moisture Equilibria and Moistrue Changes in Soils Beneath Covered Areas, A Symp. in Print. Australia: Butterworths, pp. 39-46 (1965).
[8] Krahn, and D. G. Frendlund, "On Total Matric and Osmotic Suction," J. Soil Sci., Vol.114, No.5, pp339-348 (1992).
[9] Vanapalli, S. K., Fredlund, D. G., and Pufha, D. E., "The influence of soil structure and stress history on the soil-water characteristics of a compacted till," Geotechnique, Vol.49, No.2, pp143-159 (1999).
[10] Biot, M. A.,"General Theory of Three-Dimensional Consolidation,"Journal of Applied Physics, Vol. 12, No. 2, ppl 155-164 (1941).
[11] Bishop, A. W.,"The Principle of Effective Stress,"Teknisk Ukeblad, Vol. 106, No. 39, pp. 859-863 (1959).
[12] Blight, G. E.,"Effective Stress Evaluation for Unsaturated Soils," Journal of Soil Mechanics amd Foundation Division, ASCE , Vol. 93, SM2, pp. 125-148 (1967).
[13] Jennikngs, J. E., and Burland, J. B.,"Limitations to the Use of Effective Stress in Partly Saturated Soils,"Geotechnique, Vol. 12, No. 2, pp. 125-144 (1962).
[14] Blight, G. E.,"A Study of Effective Stresses for Volume Change,"in Moisture Equilibria and Moisture Changes in Soils Beneath Covered Areas, A Symp. in Print, G. D. Aitchison, Ed. Australia: Butterworths, pp. 259-269 (1965).
[15] Burland, J. B.,"Effective Stresses in Partly Saturated,"discussion of "Some Aspects of Effective Stress in Saturated and Partly Saturated Soils,"by G. E. Blight and A. W. Bishop, Geotechnique, Vol. 14, pp. 65-68 (1964).
[16] Terzaghi, K.,"The Shear Resistance of Saturatecd Soils,"in Proc. 1st Int. Conf. Soil Mech. Found. Eng. (Cambridge, MA), Vol. 1, pp. 54-56 (1936).
[17] Fredlund, D. G., and Morgenstern, N. R.,"Stress State Variables for Unsaturated Soils,"Geotechnical Division, GT11, pp. 1415-1416 (1978).
[18] Ho, D. Y. F. and Fredlund, D. G.,"Increase in Strength due to Suction for Two Hong Kong Soils,"Proceeding of ASCE Speciality Conference on Engineering and Construction in Tropical and Residual Soils, Hawaii, pp. 263-296 (1982).
[19] Low, T. H., Faisal, Hj. Ali. and Subramaniam, R. "Parametric Studies of Slope Stability in Unsaturated Residual Soil," Thireteenth Southeast Asian Geotechnical Conference, pp.16-20 (1998).
[20] Geotechnical Control Office,"Guide to Rock and Soil Description,"Hong Kong Government Printer, pp. 189 (1988)
[21] Brand, E. W.,"Landslides in Southeast Asia , a State-of-the Art Report ,"Proceeding of the 4th International Symposium on Landslides, Toronto, Canada, pp. 17-59 (1984).
[22] Mein, R. G., and Larson, C. L.,"Modelling Infiltration during a Steady Rain,"Water Resource Research, Vol. 9, No. 2 , pp. 384-394 (1973).
[23] Lumb, P.,"Slope Failures in Hong Kong ,"Quarterly Journal Engineering Geology, Vol. 8, pp. 31-65 (1975).
[24] 「台灣省山坡地崩坍調查報告」, 山地農牧局, 民國78年。
[25] Fredlund, D. G.,"Slope Stability,"John Wiley & Sons Ltd., pp. 113-144 (1987).
[26] Brand, E. W., "Some thoughts on rain-induced slope failure," Proc. 10th ICSMFE, (3), pp.373-376 (1981).
[27] Ho, D. Y. F. and Fredlund, L. R., "Increase in strength due to section for two Hong Kong soils", Proc. ASCE Spec. Conf. Eng. and Construct. in Tropical and Residual Soils, pp.263-295, Honolulu (1982).
[28] 黃榮茂，「部份飽和夯實礫石土之抗剪強度」，國立中興大學土木工程學研究所，民國81年。
[29] Fredlund, D. G.,"The Second Technical Session, Div. Two (Flow and Shear Strength),"Proc. of the 3rd Int. Conf. On Expansive Soils, Vol. II , pp. 71-76 (1973).
[30] Hilf, J. W.,"An Investigation of Pore-Water Pressure in Compacted Cohesive Soils,"Ph. D. Dissertation, Tech. Memo. No. 654, U. S. dep. of the Interior, Bureau of Reclamation, Design and Construction Div., Denver, CO, pp.654 (1956).
[31] Bishop, A. W., and Blight, G. E.,"Some Aspects of Effective Stress in Saturated and Unsaturated Soils,"Geotechnique, Vol. 13, No. 3, pp. 177-197 (1963).
[32] Fredlund, D. G.,"Prediction of Heave in Unsaturated Soils,"Proc. of the 5th Asian Regional Conf. (Bangalore, India), pp. 19-22 (1975).
[33] 劉家男，「林口台地邊坡坍方之綜合研究」，國立台灣大學土木工程學研究所碩士論文，民國79年。
[34] Geotechnical Control Office, "Geotechnical Manual for Slopes," Hong Kong Government Printer (1984).
[35] 謝豪榮和吳建興，「林口紅土台地邊坡穩定及其土壤特性之研究」，國科會防災報告73-28號，民國74年1月。
[36] 王慶麟，「林口台地紅土邊坡破壞模式之研究」，國立台灣大學土木工程學研究所碩士論文，民國73年。
[37] Woo, S. M., Guo, W. S., Yu, K., and Moh, Z. C., "Engineering Problems of Gravel Deposit in Taiwan", Proceeding of ASCE Speciality Conference on Engineering and Construction in Tropical and Residual soils, Hawali, PP.500-518 (1982).