Debris Flow Initiation Mechanisms in Strong Earthquake Area

详细信息   

• 责任者：Qu Yongping(State Key Laboratory for Geo- Hazard Prevention and Geo- Environment Protection ; Chengdu University of Technology ; Chengdu 610059 ; China) ; Tang Chuan
• 刊名：Journal of Mountain Research
• 出版年：2012
• 卷期：30(3)
• 页码：p.336-341
• issnNo：ISSN1008-2786
• isbnNo：CN51-1516/P

摘要

Sediment supply for debris flow occurrence in the seismic zone mainly derived from loose deposits of seis- mic landslides and rockfalls. Normally the sediment supply in debris flow basin has some features such as loose structure, low density, and quick accumulation. It is much different from that in non-seismic zone. Due to change of physical property in the landslide deposits, it results in relevant change of external conditions for landslide debris transmitting in to debris flows. This paper analyzed depositional morphology and the stress environment of loose ac- cumulation of the seismic landslides based on debris flow investigation in a study area of Longchi Town, Dujianyang City that located in the Wenchuan earthquake area. Debris flow initiation mechanism under the condition of rain- storm is discussed in a basis of an analysis of statics and danamics. The relationship between the runoff water depth and the ultimate stress state during landslide deposit failure in saturated condition was showed in the formula as fol- lowing：F=（Tv-f1sina）/cos（α-26.65）. And The relationship between the runoff water depth and surface run- F off capacity was established as the formula ：H=4p.gjJf Under the conditions of the conservation of mechanical ener-gy, erosive volume model with an unit time of landslide deposit failure was established as the formula ： dV=dM/γ, o In order to apply the proposed model in actual situation, a study area in Shuida debris flow gully of Dujiangyang city of the Wenehuan earthquake area was selected. Result indicated that surface runoff depth when debris flow initiated reached O. 011 m,whieh is consistent with the result of field survey.