Initiation Mechanism of Loess Mudflows by Flume Experiments

Abstract

The structure of loess is loose, and the shear strength of loess drops sharply after contact with water. Therefore, loess mudflows have become a common geological disaster on the Chinese Loess Plateau. In order to study the initiation mode and mechanism of loess mudflows, in this study, seven sets of flume experiments were designed by controlling the slope angle and rainfall intensity. The results show that (1) when the slope angle is between 10° and 20°, there are two initiation mechanisms of loess mudflows: mudflow (large scale) and retrogressive toe sliding, and mudflow (small-scale) and retrogressive toe sliding. (2) The main method by which water infiltrates into the soil accumulation is mainly vertical infiltration, which is not affected by the slope angle and the seepage direction of the accumulation soil. (3) The liquefaction of loess is the root cause of loess mudflows. Water infiltrates into the area with an uneven density and a large amount of water accumulates in this area. Thus, the water content of the loess increases and the pore water pressure increases quickly and cannot dissipate in time, so the loess liquefies and the liquefacted area continues to spread and become larger. Thus, loess mudflows (large scale) occur. The increase in pore water pressure was captured in the seven sets of experiments. However, the order of the rising positions in the accumulation were different. This requires us to carry out tracking of the particle displacement inside the soil and the spatial changes in the internal structure of the soil in future research.

Keywords

flume tests / loess mudflow / loess liquefaction / initiation modes / initiation mechanism / engineering geology

References

[1] Castro G, Poulos S J. Factors Affecting Liquefaction and Cyclic Mobility. J. Geotech. Engng Div., 1977, 103: 501-516.

[2] Cui Y, Guo C, Zhou X. Experimental Study on the Moving Characteristics of Fine Grains in Wide Grading Unconsolidated Soil under Heavy Rainfall. J. Mt. Sci., 2017, 14(3): 417-431.

[3] Fan X M, Xu Q, Scaringi G, . A Chemo-Mechanical Insight into the Failure Mechanism of Frequently Occurred Landslides in the Loess Plateau, Gansu Province, China. Engineering Geology, 2017, 228(13): 337-345.

[4] He S Y, Wang X L, Fan H B, . The Study on Loess Liquefaction in China: A Systematic Review. Natural Hazards, 2020, 103(2): 1639-1669.

[5] Hungr O, Leroueil S, Picarelli L. The Varnes Classification of Landslide Types, an Update. Landslides, 2014, 11(2): 167-194.

[6] Ishihara K, Okusa S, Oyagi N, . Liquefaction-Induced Flow Slide in the Collapsible Loess Deposit in Soviet Tajik. Soils and Foundations, 1990, 30(4): 73-89.

[7] Iverson R M. Scaling and Design of Landslide and Debris-Flow Experiments. Geomorphology, 2015, 244: 9-20.

[8] Jin Y L, Dai F C. The Mechanism of Irrigation-Induced Landslides of Loess. Chinese Journal of Geotechnical Engineering, 2007, 29(10): 1493-1499. (in Chinese with English Abstract)

[9] Kang C, Zhang F Y, Pan F Z, . Characteristics and Dynamic Runout Analyses of 1983 Saleshan Landslide. Engineering Geology, 2018, 243: 181-195.

[10] Li P, Vanapalli S, Li T L. Review of Collapse Triggering Mechanism of Collapsible Soils Due to Wetting. Journal of Rock Mechanics and Geotechnical Engineering, 2016, 8(2): 256-274.

[11] Lian B Q, Peng J B, Zhan H B, . Formation Mechanism Analysis of Irrigation-Induced Retrogressive Loess Landslides. Catena, 2020, 195: 104441

[12] Liu T S. Loess and the Environment, 1985, Beijing: Science Press (in Chinese)

[13] Liu X, Wei X, Qin H. Characterizing Compressive Strength of Compacted Saline Loess Subjected to Freeze-Thaw Cycling with Wave Velocity. Bulletin of Engineering Geology, 2022, 81 168

[14] Liu X, Wang Y C, Nam B H. Characterizing Undrained Shear Behavior of Loess Subjected to K0 Loading Condition. Engineering Geology, 2022, 302 106634

[15] Ma P H, Peng J B, Wang Q Y, . Loess Landslides on the South Jingyang Platform in Shaanxi Province, China. Quarterly Journal of Engineering Geology and Hydrogeology, 2019, 52(4): 547-556.

[16] Ma P H, Peng J B, Wang Q Y, . The Mechanisms of a Loess Landslide Triggered by Diversion-Based Irrigation: A Case Study of the South Jingyang Platform, China. Bulletin of Engineering Geology and the Environment, 2019, 78(7): 4945-4963.

[17] Ma P H, Zhuang J Q, Zhu X H, . Flume Tests to Investigate the Initiation Mechanism of Loess Mudflows on the Chinese Loess Plateau. Frontiers in Earth Science, 2021, 9 724678

[18] Meng Z J, Ma P H, Peng J B. Characteristics of Loess Landslides Triggered by Different Factors in the Chinese Loess Plateau. Journal of Mountain Science, 2021, 18(12): 3218-3229.

[19] Niyazov, R. A., Bazarov, S. B., Akhundjanov, A. M., 2008. The Mechanism of Movement of Mud Flows in Loess Soils, Successful and Unsuccessful Cases of Forecast. In: Proceedings of the Tenth International Symposium on Landslides and Engineered Slopes. 30 June-4 July 2008, Xi’an

[20] Pei X J, Zhang X C, Guo B, . Experimental Case Study of Seismically Induced Loess Liquefaction and Landslide. Engineering Geology, 2017, 223 23-30.

[21] Peng D L, Xu Q, Liu F Z, . Distribution and Failure Modes of the Landslides in Heitai Terrace, China. Engineering Geology, 2018, 236: 97-110.

[22] Peng J B, Fan Z J, Wu D, . Heavy Rainfall Triggered Loess-Mudstone Landslide and Subsequent Debris Flow in Tianshui, China. Engineering Geology, 2015, 186: 79-90.

[23] Peng J B, Ma P H, Wang Q Y, . Interaction between Landsliding Materials and the Underlying Erodible Bed in a Loess Flowslide. Engineering Geology, 2018, 234: 38-49.

[24] Peng J B, Wang S K, Wang Q Y, . Distribution and Genetic Types of Loess Landslides in China. Journal of Asian Earth Sciences, 2019, 170: 329-350.

[25] Pu X W, Wan L M, Wang P. Initiation Mechanism of Mudflow-Like Loess Landslide Induced by the Combined Effect of Earthquakes and Rainfall. Natural Hazards, 2021, 105(3): 3079-3097.

[26] Wang G H, Sassa K. Pore-Pressure Generation and Movement of Rainfall-Induced Landslides: Effects of Grain Size and Fine-Particle Content. Engineering Geology, 2003, 69(1/2): 109-125.

[27] Wang G H, Zhang D X, Furuya G, . Pore-Pressure Generation and Fluidization in a Loess Landslide Triggered by the 1920 Haiyuan Earthquake, China: A Case Study. Engineering Geology, 2014, 174: 36-45.

[28] Wu K L, Chen N S, Hu G S, . Failure Mechanism of the Yaoba Loess Landslide on March 5, 2020: The Early-Spring Dry Spell in Southwest China. Landslides, 2021, 18(9): 3183-3195.

[29] Xu L, Dai F C, Tu X B, . Occurrence of Landsliding on Slopes where Flowsliding Had Previously Occurred: An Investigation in a Loess Platform, North-West China. Catena, 2013, 104: 195-209.

[30] Yuan B, Chen W W, Tang Y Q, . Experimental Study on Gully-Shaped Mud Flow in the Loess Area. Environmental Earth Sciences, 2015, 74(1): 759-769.

[31] Zhang F Y, Kong R, Peng J B. Effects of Heating on Compositional, Structural, and Physicochemical Properties of Loess under Laboratory Conditions. Applied Clay Science, 2018, 152: 259-266.

[32] Zhang F Y, Peng J B, Wu X G, . A Catastrophic Flowslide that Overrides a Liquefied Substrate: The 1983 Saleshan Landslide in China. Earth Surface Processes and Landforms, 2021, 46(10): 2060-2078.

[33] Zhang F Y, Wang G H, Kamai T, . Undrained Shear Behavior of Loess Saturated with Different Concentrations of Sodium Chloride Solution. Engineering Geology, 2013, 155: 69-79.

[34] Zhang F Y, Wang G H, Kamai T, . Effect of Pore-Water Chemistry on Undrained Shear Behaviour of Saturated Loess. Quarterly Journal of Engineering Geology and Hydrogeology, 2014, 47(3): 201-210.

[35] Zhang, Z. Y., Chen S. M., Tao L. J., 2002. The Sale Mountain Landslide, Gansu Province, China. In: Evans, S. G., DeGraff, J. V., eds., Catastrophic Landslides, Geological Society of America. Reviews in Engineering Geology, XV:149–173

[36] Zhu X H, Peng J B, Liu B X, . Influence of Textural Properties on the Failure Mode and Process of Landslide Dams. Engineering Geology, 2020, 271 105613

[37] Zhuang J Q, Peng J B, Zhu Y. Study of the Effects of Clay Content on Loess Slope Failure Mode and Loess Strength. Bulletin of Engineering Geology and the Environment, 2021, 80(3): 1999-2009.