强震区泥石流启动机制  

Debris Flow Initiation Mechanisms in Strong Earthquake Area

作　　者：屈永平[1] 唐川[1] 王金亮[1] 唐宏旭[1] 刘洋[1] 陈海龙[1] 黄伟[1] 

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《山地学报》2012年第3期336-341,共6页Mountain Research

基　　金：国家973计划(2011CB409903);国家科技支撑计划课题(2011BAK12B01)~~

摘　　要：地震区的泥石流物源主要来源于滑坡、崩塌等松散体,具有结构疏松,密实度低,堆积时间短等特点,与非地震环境中的滑坡、崩塌堆积体的结构有所不同,堆积体的物理力学性质发生了改变,堆积体转换为泥石流所需的外界条件也相应的改变。以汶川地震区都江堰市龙池镇典型泥石流灾害为例,分析了地震滑坡、崩塌松散体的堆积形态和堆积体的应力环境。从静力学和动力学角度分析堆积体在强降雨条件下的起动特征,探讨了降雨作用形成的地表径流水深与堆积体失稳时的应力极限状态的关系。分析得出沟道岸坡滑坡堆积体发生侵蚀时的地表径流力为F=(τ1f-f1sinα)/cos(α-26.65),并建立径流水深与地表径流力的关系:H=F/4ρsgJ。分析在动量守恒条件下,堆积体单位时间内的侵蚀体积dV=dM/γs模型。为了进一步探讨在实际现场的应用,以汶川地震区都江堰市的水打沟泥石流为例,分析发生泥石流时的地表径流水深为0.011 m,其结论与实际调查结果基本一致。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.

关 键 词：泥石流 滑坡堆积体 岩土特性 地表径流 启动机制 

分 类 号：P642.23[天文地球—工程地质学]