Effects of the Hysteresis of Soil-Water Characteristic Curve on Unsaturated Soil Slopes Stability

doi:None

All Issue

2010 Vol.47, Issue 3 Preview Page Next Page

Effects of the Hysteresis of Soil-Water Characteristic Curve on Unsaturated Soil Slopes Stability 함수특성곡선의 이력현상이 불포화 사면의 안정성에 미치는 영향: 백환조, 김경만, 김대훈
Hwanjo Baek, Kyung-Man Kim and Dae-Hoon Kim

30 June 2010. pp. 349-358

PDF

Abstract

The soil-water characteristic curves for wetting and drying processes of weathered granitic soils was obtained. A numerical study was conducted for stability analysis of unsaturated soil slope on continuous rainfall, and impacts of hysteresis of soil-water characteristic curve (SWCC) were analyzed. Granitic soil samples were prepared in acrylic containers with sensors installed for soil suction and volumetric water content measurements. Soil samples were saturated under direct rainfall, then were dried out at room temperature. Based on the field data, the drying and wetting SWCC’s were obtained adopting the Fredlund and Xing equation (1994), and a numerical study was conducted for unsaturated soil slope stability due to continuous rainfall using equation of Vanapalli et. al. (1996) relating the shear strength of unsaturated soils. Consequently, the hysteresis of SWCC was clearly defined and as result of numerical analysis, factor of safety of slope was different according to the wetting process and drying process of SWCC. Therefore, considering these properties of unsaturated soil, it is desirable to apply the SWCC of the wetting process and drying process respectively to the site conditions.

Keywords

SWCC

Hysteresis

Unsaturated soil

Shear strength of unsaturated soils

본 연구에서는 국내 대표적 지반인 화강풍화토의 습윤 및 건조과정의 함수특성곡선을 얻고, 함수특성의 이력현상이 사면의 안전율에 미치는 영향을 분석하기위해 수치해석을 실시하였다. 시료의 함수특성곡선을 얻기 위해 체적함수비와 흡수력을 측정할 수 있는 센서를 연결한 토조를 제작하여 강우에 의한 자료를 획득하였으며, 이후 실온에서 건조시키는 과정에서 얻은 자료를 결합하여 국내 화강풍화토에 적합성이 높은 Fredlund and Xing(1994)의 경험방정식을 이용해 습윤 및 건조 과정의 함수특성곡선을 완성하였다. 또한 국내 화강풍화토에 적합성이 높은 불포화토의 전단강도와 관련된 Vanapalli et al.(1996)의 제안식이 적용 가능한 프로그램을 사용하여 지속강우시 사면의 안전율에 관한 수치해석적 연구를 실시하였다. 그 결과 함수특성곡선의 습윤 과정과 건조 과정에 따라 침투속도가 달라 안전율의 차이가 나타남을 확인 할 수 있었고 불포화토의 특성을 고려한 보다 합리적인 설계나 안정성 검토에는 강우침투사면과 같은 습윤 과정에서는 습윤 과정의 함수특성곡선을, 건조 과정에서는 건조과정의 함수특성곡선을 적용하는 것이 합당할 것으로 판단된다.

키워드

함수특성곡선

이력현상

불포화토

불포화 전단강도

References

김윤기, 2003, 투수시험결과 해석에 의한 불포화 풍화토의 투수성에 관한 연구, 공학석사학위논문, 한국과학기술원.
성상규, 이인모, 2003, “화강풍화잔적토의 불포화전단강도에 미치는 순연직응력의 영향,” 한국지반공학회논문집, 제19권 2호, pp. 27-38.
신방웅, 이홍길, 2005, “해안매립지 대심도 굴착지역의 불포화 함수특성에 따른 침투류 거동,” 한국지반공학회논문집, 제6권 4호, pp. 47-58.
신은철, 이학주, 오영인, 2004, “불포화 준설매립 지반의 흙-수분 특성곡선 및 불포화 투수계수 예측,” 한국지반공학회논문집, 제20권 1호, pp. 109-120.
오진규, 2007, 강우침투를 고려한 불포화 사면 설계 방안, 공학석사학위논문, 한국과학기술원.
이관영, 2004, 강우특성을 고려한 불포화토 사면의 안정성 해석, 공학석사학위논문, 대진대학교.
최경림, 2007, 화강풍화토에 대한 함수특성곡선으로부터 불포화투수계수 유추에 관한 연구, 공학석사학위논문, 한국과학기술원.
Christensen, H. R., 1944, “Permeability capillary potential curves for three prairie soils,” Soil Science, Vol. 57 No. 5, pp. 381-390.
Fredlund, D. G., Morgenstern, N. R., and Widger, R. A., 1978, “The shear strength of unsaturated soils,” Canadian Geotechnical Journal, Vol. 15, pp. 313-321.
Fredlund, D. G., Xing, 1994, “Equations for the Soil-Water Characteristic Curve,” Canadian Geotechnical Journal, Vol. 31 No. 4, pp. 521-532.
Fredlund, D. G., H. Rahardjo, 1995, “Soil Mechanics For Unsaturated Soils,” Wiley and Sons, Inc.
Guymon, L. G. 1994, “Unsaturated Zone Hydrology,” Prentice Hall, Englewood Cliffs, New Jersey, p. 210.
Geo-slope, 2007, “User’s Guide for SEEP/W 2007,” Geoslope International Ltd, Canada.
Geo-slope, 2007, “User’s Guide for SLOPE/W 2007,” Geoslope International Ltd, Canada.
Kumar, S. and Malik, R. S. 1990, “Verification of Quick Capillary Rise Approach for Determining Pore Geometrical Characteristics in Soils of Varying Texture,” Soil Science, Vol. 150, No. 6, pp. 874-882.
Laroussi, C. H. and De Backer, L. W., 1979, “Relations between geometrical properties of glass bead media and their main ψ(θ) hysteresis loops,” Soil Science Society of America Journal, Vol. 43, pp. 646-650.
Letey, J., Osborn, J., and Pelishek, R.E., 1962, “Measurement of liquid-solid contact angles in soil and sand,” Soil Science, Vol. 93, pp. 149-153.
Liakopoulos, A. C., 1965, “Transient flow through unsaturated porous media, D. Eng. Dissertation,” University of California, Berkeley, Calif.
Ng, K. L. a. and Shi, Q., 1998, “A numerical investigation of the stability of the stability of unsaturated soil slopes subjected to transient seepage,” Computer and Geotechnics, Vol. 22, pp. 1-28.
Ning Lu, William J. Likos, 2004, “Unsaturated Soil Mechanics,” Wiley and Sons, Inc., pp. 185-186.
Vanapalli, S. K., Fredlund, D. G., Pufahl, D. E., and Clifton, A. W., 1996, “Model for the prediction of shear strength with respect to soil suction,” Canadian Geotechnical Journal, Vol. 33 No. 3, pp. 379-392.
Vanapalli, S. K., Fredlund, D. G. 2000, “Comparison of empirical procedures to predict the shear strength of unsaturated soils uses the soil-water characteristic curve,” American Society of Civil Engineers, Special Publication, Vol. 99, pp. 195-209.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 47
No :3
Pages :349-358

[1] 김윤기, 2003, 투수시험결과 해석에 의한 불포화 풍화토의 투수성에 관한 연구, 공학석사학위논문, 한국과학기술원.

[2] 성상규, 이인모, 2003, “화강풍화잔적토의 불포화전단강도에 미치는 순연직응력의 영향,” 한국지반공학회논문집, 제19권 2호, pp. 27-38.

[3] 신방웅, 이홍길, 2005, “해안매립지 대심도 굴착지역의 불포화 함수특성에 따른 침투류 거동,” 한국지반공학회논문집, 제6권 4호, pp. 47-58.

[4] 신은철, 이학주, 오영인, 2004, “불포화 준설매립 지반의 흙-수분 특성곡선 및 불포화 투수계수 예측,” 한국지반공학회논문집, 제20권 1호, pp. 109-120.

[5] 오진규, 2007, 강우침투를 고려한 불포화 사면 설계 방안, 공학석사학위논문, 한국과학기술원.

[6] 이관영, 2004, 강우특성을 고려한 불포화토 사면의 안정성 해석, 공학석사학위논문, 대진대학교.

[7] 최경림, 2007, 화강풍화토에 대한 함수특성곡선으로부터 불포화투수계수 유추에 관한 연구, 공학석사학위논문, 한국과학기술원.

[8] Christensen, H. R., 1944, “Permeability capillary potential curves for three prairie soils,” Soil Science, Vol. 57 No. 5, pp. 381-390.

[9] Fredlund, D. G., Morgenstern, N. R., and Widger, R. A., 1978, “The shear strength of unsaturated soils,” Canadian Geotechnical Journal, Vol. 15, pp. 313-321.

[10] Fredlund, D. G., Xing, 1994, “Equations for the Soil-Water Characteristic Curve,” Canadian Geotechnical Journal, Vol. 31 No. 4, pp. 521-532.

[11] Fredlund, D. G., H. Rahardjo, 1995, “Soil Mechanics For Unsaturated Soils,” Wiley and Sons, Inc.

[12] Guymon, L. G. 1994, “Unsaturated Zone Hydrology,” Prentice Hall, Englewood Cliffs, New Jersey, p. 210.

[13] Geo-slope, 2007, “User’s Guide for SEEP/W 2007,” Geoslope International Ltd, Canada.

[14] Geo-slope, 2007, “User’s Guide for SLOPE/W 2007,” Geoslope International Ltd, Canada.

[15] Kumar, S. and Malik, R. S. 1990, “Verification of Quick Capillary Rise Approach for Determining Pore Geometrical Characteristics in Soils of Varying Texture,” Soil Science, Vol. 150, No. 6, pp. 874-882.

[16] Laroussi, C. H. and De Backer, L. W., 1979, “Relations between geometrical properties of glass bead media and their main ψ(θ) hysteresis loops,” Soil Science Society of America Journal, Vol. 43, pp. 646-650.

[17] Letey, J., Osborn, J., and Pelishek, R.E., 1962, “Measurement of liquid-solid contact angles in soil and sand,” Soil Science, Vol. 93, pp. 149-153.

[18] Liakopoulos, A. C., 1965, “Transient flow through unsaturated porous media, D. Eng. Dissertation,” University of California, Berkeley, Calif.

[19] Ng, K. L. a. and Shi, Q., 1998, “A numerical investigation of the stability of the stability of unsaturated soil slopes subjected to transient seepage,” Computer and Geotechnics, Vol. 22, pp. 1-28.

[20] Ning Lu, William J. Likos, 2004, “Unsaturated Soil Mechanics,” Wiley and Sons, Inc., pp. 185-186.

[21] Vanapalli, S. K., Fredlund, D. G., Pufahl, D. E., and Clifton, A. W., 1996, “Model for the prediction of shear strength with respect to soil suction,” Canadian Geotechnical Journal, Vol. 33 No. 3, pp. 379-392.

[22] Vanapalli, S. K., Fredlund, D. G. 2000, “Comparison of empirical procedures to predict the shear strength of unsaturated soils uses the soil-water characteristic curve,” American Society of Civil Engineers, Special Publication, Vol. 99, pp. 195-209.

Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

All Issue