Hydraulic mechanism of gully bed erosion by debris flow in rainfall
WU Yong1,2,3, PEI Xiang-jun3, HE Si-ming1, LI Xin-po1,3
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 and
Technology, Xuzhou 221008, China|3. State Key Laboratory of Geohazard Prevention and Geoenvironment Protention,
Chengdu University of Technology, Chengdu 610041, China
Based on the water lever model of debris flow established according to hydrology, and by aid of hydraulic theory, the erosion mechanism of gully bed under flow shear stress and seepage hydraulic was studied. After studying the calculation methods for flow shear stress, pore water pressure, static pressure and gully bed weight, the critical erosion depth of gully bed by debris flow was proposed. By discussing the influences of rainfall pattern, gully geometric parameters and flow property to debris flow pattern and its erosion characteristics with an example, the way to calculate erosion was illustrated. The result indicates that the erosion becomes weak with the incensement of depth of base material, and only occurs above on a critical erosion depth in gully bed|with different rainfall conditions, gully geometric character and debris flow property, the flow depth and velocity changes greatly, which effects the gully bed erosion directly.
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