›› 2012, Vol. 33 ›› Issue (10): 3043-3050.

• Geotechnical Engineering • Previous Articles     Next Articles

Analysis of condition of startup of gully debris flow after earthquake—The hydraulic mechanism of instability of loose deposits in rainfall

WU Yong1, 2, 3, HE Si-ming1, PEI Xiang-jun3, LI Xin-po1, 3   

  1. 1. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 2. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Xuzhou, Jiangsu 221008, China; 3. State Key Laboratory of Geohazard Prevention and Geoenvironment Protention, Chengdu University of Technology, Chengdu 610041, China
  • Received:2011-05-27 Online:2012-10-10 Published:2012-10-19

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Abstract: Because large quantities of loose deposits were accumulated in gully after “5•12” Earthquake, the occurrence probability of gully debris flow is enhanced greatly in rainfall. However, due to the special conditions of provenance and disaster environment, the traditional theory cannot be used to expound the mechanism of gully debris flow and prevent the disaster effectively as ever after the event. Here, based on hydrology, the hydrological model of ground water table in loose deposits is established first. Then by aid of hydraulic theory, the change of hydraulic characteristics and the variation of hydraulic power with the rising of groundwater level are analyzed. Furthermore, the calculation formulas of hydrodynamic and hydrostatic pressure are also proposed. Finally, by applying infinite slope theory in calculation of sliding force, anti-sliding force and residual sliding force acting on each segment, the failure mechanism of accumulation body is illustrated clearly with an example. The result indicates the failure of loose deposits in rainfall is the result of increase of the hydraulic power with the rising of groundwater level. Those deposits which have small coefficient, gentle slope, narrow-deep gully and large basin would be easy to fail because of its high hydraulic pressure generating in rainstorm, and the failure modes can be divided into two types according to residual sliding force as pushing failure and hauling failure.

Key words: rainfall after earthquake, debris flow, loose deposits, gully hydrologic model, hydraulic mechanism

CLC Number: 

  • U 418.5+6
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