Abstract：The variation of groundwater levels in a slope is usually used as the major parameter for the monitoring of slope stability. But its influence on the safety factor of a slope is seldom examined. Most indices used in commercial slope stability monitoring devices only show potential dangerous situations based upon experience without any corresponding displacement information. In this study, we use both numerical analysis method and limit equilibrium method to analyze the relationship among groundwater levels, stress, strain, and safety factor of sandy slopes. So, the influence of groundwater water levels on the sandy slope stabilities can be evaluated. It is found in different internal friction angles of sands that the safety factors of the slope will drop down rapidly when the critical water level is approached. This conclusion can be presented with two normalized parameters of FS/tan? and Hw/H. Therefore two rapid assessment charts for evaluating the stability of sandy slopes are established. The method recommended in this study can also be used to evaluate the safety of real slopes which you don’t have detailed influence factors.
[1] 洪如江. 贺伯台风、新中横公路与坍方及土石流灾害[J]. 地工技术, 1996, 57: 25–30. (HUNG Ju-jiang. TYPHOON Herb, the New-Central-Cross-Island-Highway and slopeland failures in central Taiwan[J]. Sino-Geotechnics, 1996, 57: 25–30. (in Chinese))[2] 李咸亨, 吴泰庆. 莫拉克风灾之危险边坡预警省思及整治对策[J]. 营建知讯, 2010, 324: 36–41. (LEE Hsien-heng, WU Tai-ching. Warning index and improvement countermeasure for a dangerous slope learned from Molake typhoon 2008[J]. Construction News Record, 2010, 324: 36–41. (in Chinese))[3] MICHALOWSKI R L. Slope stability analysis：a kinematical approach[J]. Géotechnique, 1995, 45(2): 283–293.[4] HUANG S L, YAMASAKI K. Slope failure analysis using local minimum factor-of-safety approach[J]. Journal of Geotechnical Engineering, ASCE, 1993, 119(12): 1974–1987.[5] MATSUI T, SAN K C. Finite element slope stability analysis by shear strength reduction technique[J]. Soils and Foundations, 1992, 32(1): 59–70.[6] DAWSON E M, ROTH W H, DRESCHER A. Slope stability analysis by Strength Reduction[J]. Géotechnique, 1999, 49(6): 835–840.[7] 陈志昌. FLAC程序应用于土壤边坡稳定分析[D]. 桃园: 中原大学, 2001. (CHEN Jyh-chang. Stability analysis of soil slopes using FLAC[D]. Taoyuan: Chung Yuan University, 2001. (in Chinese))[8] 范嘉程, 冯道伟. 以有限元素法探讨暴雨时边坡之稳定分析[J]. 地工技术, 2003, 95: 61–74. (FAN Chia-cheng, FENG Tao-wei. Application of finite element procedures on the slope stability analysis in stormy condition[J]. Sino-Geotechnics, 2003, 95: 61–74. (in Chinese))[9] ITASCA Consulting Group, Inc FLAC: Fast Lagrangian Analysis of Continua, Fish in FLAC, Version 4.0[M]. Minneapolis: ITASCA Consulting Group, 2000.[10] U S Department of Transportation,Federal Highway Administration. PC-STABL5M user guide VA22101-2296[M]. Mclean: Turner-Fairbank Highway Research Center, 1989. [11] SPENCER E. A method of analysis of the stability of embankments assuming parallel inter-slice forces[J]. Géotechnique, 1967, 17: 11–26.[12] VERMEER K H, R de Borst. Non-associated plasticity for soils, concrete and rock[J]. Heron, 1984, 29(3): 3–64.[13] BOWLES J E. Foundation analysis and design[M]. 4th ed. New York: McGraw-Hill Inc, 1988.[14] DAS B M. Principles of foundation engineering[M]. 2nd ed. Boston: PWS Publishing Company, 1997.[15] ORENSE R P, SHIMOMA S, MAEDA K, et al. Instrumented model slope failure due to water seepage[J]. Journal of Natural Disaster Science, 2004, 26: 15–26.[16] NISHIGAKI M, TOHARI A, KOMATSU M. Laboratory rainfall-induced slope failure with moisture content measurement[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2007, 133(5): 575–587.[17] 吴俊纬. 地下水位对砂质边坡之连续性破坏研究[D]. 台北: 台湾科技大学, 2009. (WU Chun-wei. The influence of groundwater level on the progressive failure in a sandy slope[D]. Taipei: National Taiwan University of Science and Technology, 2009. (in Chinese))[18] HORI T, HOHRI Y, KOHGO Y. Model test for slope failure under seepage and analysis of elasto-plastic model for unsatulated soil[C]// Proceedings of the Japan National Conference on Geotechnical Engineering, 2003: 1283–1284.
