Research on Analysis Method for Stability of Perched Transient Saturated Slope

JIANG Zhong-ming1,2 LI Xiao-fan1,3 WU Zhong-cai4

(1.School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha, Hunan, China 410004)
(2.Key Laboratory of Water-sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha University of Science & Technology, Changsha, Hunan, China 410004)
(3.Water Resources Department of Hunan Province, Changsha, Hunan, China 410007)
(4.Shaoyang Hydro & Power Design Institution, Shaoyang, Hunan, China 422000)

【Abstract】In order to analyze the stability of the transient saturated slope caused by rainfall infiltration, the instability mechanism of transient saturated slope under the condition of rainfall infiltration was analyzed by considering the influence of unit weight, matric suction and transient water pressure. The distribution law of transient water pressure in the transient saturated area was discovered, and the corresponding computing methods for transient water pressure were proposed. A modification on Janbu limit equilibrium method with the consideration of transient water pressure, matric suction and great changes was made by dint of the distribution condition whether the slope was situated at the perched transient saturated area. And a routine which could search both circular and non-circular sliding surfaces was programmed for the stability analysis of transient saturated slope. The variation law of stability factor and sliding mechanism of perched transient saturation slope were investigated. The results show that the stability is mainly influenced by matric suction at the beginning of rainfall period, as the depth of transient saturated area is shallow. With the increase of the depth of the transient saturated area, transient water pressure in the slope becomes the main factor controlling the slope stability, and the safety factor of the slope gradually decreases. The safety factor of non-circular type is smaller than that of circular type with the increase of the depth of the transient saturated area. Besides, the potential sliding surface of non-circular sliding mode becomes shallower with the decrease of the depth of the transient saturated area. It is also indicated that under the same condition, the depth of non-circular sliding surface is always smaller than that of circular sliding surface with the increase of the depth of the transient saturated area. The depth of the most dangerous mansard sliding surface decreases with the increase of the transient saturated area. The depth of the circular sliding surface decreases first and then increases. This variation trend is related to the transient water pressure on the bottom of the slice and the shear strength parameters. A shallow non-circular slice mode is more easily generated in the perched transient saturated slope.

【Keywords】 road engineering; perched transient saturated slope; improved Janbu method; transient water pressure; instability mode;


【Funds】 National Natural Science Foundation of China (41422207) Scientific Research Innovation Project for Graduate Students in Hunan Province (CX2016B402)

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    [1] LI Jia, GAO Guang-yun, HUANG Xue-feng. Experimental Research on Immersion for Unsaturated Intact Loess Slope [J]. Chinese Journal of Rock Mechanics and Engineering, 2011, 30 (5): 1043–1048 (in Chinese).

    [2] ZHOU Jia-wen, XU Wei-ya, DENG Jun-ye, et al. Stability Analysis of Slope Under the Condition of Rainfall Infiltration [J]. Journal of Hydraulic Engineering, 2008, 39 (9): 1066–1073 (in Chinese).

    [3] COLLINS B D, ZNIDARCIC D. Stability Analyses of Rainfall Induced Landslides [J]. Journal of Geotechnical and Geoenvironmental Engineering, 2004, 130 (4): 362–372.

    [4] JIANG Zhong-ming, ZENG Ling, FU Hong-yuan, et al. Seepage Characteristics of Thick Coating Slope in Raining Condition [J]. Journal of Central South University: Science and Technology, 2012, 43 (7): 2782–2788 (in Chinese).

    [5] TAN Xin, CHEN Shan-xiong, YANG Ming. Saturated-unsaturated Seepage Analysis of Slope Under Rainfall [J]. Rock and Soil Mechanics, 2003, 24 (3): 381–384 (in Chinese).

    [6] KIM J, JEONG S, RICHARD A R. Instability of Partially Saturated Soil Slopes Due to Alteration of Rainfall Pattern [J]. Engineering Geology, 2012 (147/148): 28–36.

    [7] JIANG Zhong-ming, WU Zhong-cai, FENG Shu-rong, et al. Limit Equilibrium Method for Stability Analysis of Slope with Transient Saturated Area [J]. Journal of Hydraulic Engineering, 2015, 46 (7): 773–782 (in Chinese).

    [8] LI Ning, XU Jian-cong, QIN Ya-zhou. Research on Calculation Model for Stability Evaluation of Rainfall-induced Shallow Landslides [J]. Rock and Soil Mechanics, 2012, 33 (5): 1485–1490 (in Chinese).

    [9] ZUO Zi-bo, ZHANG Lu-lu, WANG Jian-hua. Model Tests on Rainfall-induced Colluvium Landslides: Effects of Particle-size Distribution [J]. Chinese Journal of Geotechnical Engineering, 2015, 37 (7): 1319–1327 (in Chinese).

    [10] HU Ming-jian, WANG Ren, ZHANG Ping-cang. Primary Research on the Effect of Rainfall on Landslide—Take the Slope Piled by Old Landslide in Jiangjiagou Valley as Example [J]. Chinese Journal of Geotechnical Engineering, 2001, 23 (4): 454–457 (in Chinese).

    [11] WANG G H, SASSA K. Pore-pressure Generation and Movement of Rainfall-induced Landslides:Effects of Grain Size and Fine-particle Content [J]. Engineering Geology, 2003, 69 (1/2): 109–125.

    [12] CHANG Jin-yuan, BAO Han, WU Fa-quan, et al. Discussion on Stability of Shallow Landslide Under Rainfall [J]. Rock and Soil Mechanics, 2015, 36 (4): 995–1001 (in Chinese).

    [13] Xu Q J, Zhang L M. The Mechanism of a Railway Landslide Caused by Rainfall [J]. Landslides, 2010, 7 (2): 149–156.

    [14] FREDLUND D G, RAHARDJO H. Soil Mechanics for Unsaturated Soils [M]. Beijing:China Architecture & Building Press, 1997 (in Chinese).

    [15] WU Jun-jie, WANG Cheng-hua, LI Guang-xin. Influence of Matric Suction in Unsaturated Soils on Slope Stability [J]. Rock and Soil Mechanics, 2004, 25 (5): 732–736, 744 (in Chinese).

    [16] LUO Xiao-hui, YE Huo-yan. Stability Analysis of Soil Slope Considering Matric Suction [J]. Rock and Soil Mechanics, 2007, 28 (9): 1919–1922 (in Chinese).

    [17] QI Guo-qing, HUANG Run-qiu, SU Bao-yu, et al. Numeric Simulation on Rainfall Infiltration on Rock Slope [J]. Chinese Journal of Rock Mechanics and Engineering, 2003, 22 (4): 625–629 (in Chinese).

    [18] JIANG Zhong-ming, XIONG Xiao-hu, ZENG Ling. Unsaturated Seepage Analysis of Slope Under Rainfall Condition Based on FLAC3D [J]. Rock and Soil Mechanics, 2014, 35 (3): 855–861 (in Chinese).

    [19] FU Hong-yuan, ZENG Ling, JIANG Zhong-ming, et al. Developing Law of Transient Saturated Area of Highway Slope Under Rainfall Condition [J]. China Journal of Highway and Transport, 2012, 25 (3): 59–64 (in Chinese).

    [20] DENG Dong-ping, LI Liang, ZHAO Lian-heng. A New Method of Sliding Surface Searching for General Stability of Slope Based on Janbu Method [J]. Rock and Soil Mechanics, 2011, 32 (3): 891–898 (in Chinese).

    [21] CHEN Yun-min, WEI Xin-jiang, LI Yu-chao. Location Non-circular Critical Slip Surfaces By Partiicies Swarm Optimization Algorithm [J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25 (7): 1443–1449 (in Chinese).

    [22] TAN Xin, DING Wan-tao, LI Shu-cai.A New Global Optimization Algorithm for Analysis of Non-circular Slip Surface [J]. Chinese Journal of Underground Space and Engineering, 2005, 24 (12): 2060–2064 (in Chinese).

This Article


CN: 61-1313/U

Vol 31, No. 02, Pages 48-56

February 2018


Article Outline


  • 0 Introduction
  • 1 Analysis method for the stability of perched transient saturated slope
  • 2 Calculation methods of transient water pressure
  • 3 Program development forlimit equilibrium analysis of perched transient saturated slope
  • 4 Stability characteristics of transient saturated slope
  • 5 Conclusions
  • References