Long runout mechanism of the Shenzhen 2015 landslide: insights from a two-phase flow viewpoint
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A catastrophic landslide occurred at Hongao dumpsite in Guangming New District of Shenzhen, South China, on December 20, 2015. An estimated total volume of 2.73×106 m3 of construction spoils was mobilized during this event. The landslide traveled a long distance on a low-relief terrain. The affected area was approximately 1100 m in length and 630 m in width. This landslide made 33 buildings destroyed, 73 people died and 4 people lost. Due to the special dumping history and other factors, soil in this landfill is of high initial water content. To identify the major factors that attribute to the long runout character, a two-phase flow model of Iverson and George was used to simulate the dynamics of this landslide. The influence of initial hydraulic permeability, initial dilatancy, and earth pressure coefficient was examined through numerical simulations. We found that pore pressure has the most significant effect on the dynamic characteristics of Shenzhen landslides. Average pore pressure ratio of the whole basal surface was used to evaluate the degree of liquefaction for the sliding material. The evolution and influence factors of this ratio were analyzed based on the computational results. An exponential function was proposed to fit the evolution curve of the average pore pressure ratio, which can be used as a reasonable and simplified evaluation of the pore pressure. This fitting function can be utilized to improve the single-phase flow model.
KeywordsDynamics Landslide Long runout Pore pressure Two-phase
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This paper was supported by the National Key R&D Program of China (Grant Nos. 2017YFC1502502, 2017YFC1502506), National Nature Science Foundation of China (Grant Nos. 41672318, 51679229, 41372331), and 135 Strategic Program of the Institute of Mountain Hazards and Environment, CAS (Grant No. SDS-135-1701). It was also supported by Youth Innovation Promotion Association of the Chinese Academy of Sciences (2018405).
- Evans SG, Hungr O, Clague JJ (2001) Dynamics of the 1984 rock avalanche and associated distal debris flow on Mount Cayley, British Columbia, Canada; implications for landslide hazard assessment on dissected volcanoes. Engineering Geology 61(1): 29–51. https://doi.org/10.1016/S0013-7952(00)00118-6 CrossRefGoogle Scholar
- George DL, Iverson RM (2011) A two–phase debris–flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore–fluid pressure. In: Genevois R, Hamilton DL, Prestininzi, A (Eds.), Proceedings of the 5th International Conference on Debris Flow Hazards Mitigation, 14–17 June, 2011. Padova, Italy. Italian Journal of Engineering Geology and Environment pp. 415–424. https://doi.org/10.4908/IJEGE.2011-03.b-047
- George DL, Iverson RM (2014) A depth–averaged debris–flow model that includes the effects of evolving dilatancy. II. Numerical predictions and experimental tests. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470(2170): 20130820–20130820. https://doi.org/10.1098/rspa.2013.0820 CrossRefGoogle Scholar
- Iverson RM (2005) Regulation of landslide motion by dilatancy and pore pressure feedback. Journal of Geophysical Research 110(F2). https://doi.org/10.1029/2004jf000268
- Kaitna R, Palucis MC, Yohannes B, et al. (2016) Effects of coarse grain size distribution and fine particle content on pore fluid pressure and shear behavior in experimental debris flows. Journal of Geophysical Research: Earth Surface 121(2): 415–441. https://doi.org/10.1002/2015JF003725 Google Scholar
- Major JJ, Iverson RM (1999) Debris–flow deposition: Effects of pore–fluid pressure and friction concentrated at flow margins. Geological Society of America Bulletin 111(10): 1424–1434. https://doi.org/10.1130/0016-7606(1999)111<1424:DFDEOP>2.3.CO;2 CrossRefGoogle Scholar
- Okada Y, Sassa K, Fukuoka H (2000) Liquefaction and the steady state of weathered granitic sands obtained by undrained ring shear tests: a fundamental study of the mechanism of liquidized landslides. Journal of Natural Disaster Science 22(2): 75–85. https://doi.org/10.2328/jnds.22.75 CrossRefGoogle Scholar
- Pudasaini SP (2012) A general two–phase debris flow model. Journal of Geophysical Research 117(F3). https://doi.org/10.1029/2011jf002186
- Reynolds O (1885) On the dilatancy of media composed of rigid particles in contact. With experimental illustrations. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 20(127):469–481Google Scholar
- State Administration of Work Safety (2016) The Investigation report of “12·20” extremely large accident of landfill landslide at Guangming new district of Shenzhen, Guangdong. Available online at: https://doi.org/www.chinasafety.gov.cn/newpage/newfiles/20160715szsg.pdf, accessed on 2017-03-0.Google Scholar
- Sassa K (2002) Mechanism of rapid and long traveling flow phenomena in granular soils. In: Proceedings of the UNESCO/IGCP International Symposium on Landslide Mitigation and Protection of Cultural and Natural Heritage, Kyoto, Japan. pp 21–25.Google Scholar
- Terzaghi K (1944) Theoretical soil mechanics. Chapman And Hali, Limited John Wiler And Sons, Inc., New York.Google Scholar