汶川强震区泥石流特征研究——以银厂沟东林寺-海汇桥段为例

Characteristics of Earthquake Debris Flow in Wenchuan Earthquake Area——A Case from Donglinsi-Haihui Bridge in Yinchang Gully

汶川大地震导致大量崩塌和滑坡等地质灾害,为泥石流的发生提供了丰富的物质来源,在强降雨条件下,泥石流的暴发几率较地震前大大增加。通往银厂沟景区必经之路的东林寺-海汇桥段,位于龙门山山前断裂带上,在2008、2009和2010年3个雨季的强降雨作用下,该段10.2 km长度范围内的11条沟不同程度暴发泥石流灾害,均属典型的地震泥石流。泥石流特征明显,主要表现在:(1)频率高,暴发点多,规模大小不一;(2)流体性质一般以粘性为主;(3)泥石流的活动范围与降雨、地形因素关系密切;(4)泥石流危害形式有冲毁、淤埋、堵塞主河等多种形式。继"5.12"地震后,连续3年的地震灾区泥石流活动显示,地震区泥石流已进入高发期,该时期可能持续5～10 a,甚至更长,对可能遭遇泥石流的区域,应做好持久性防灾减灾工作。

The secondary disasters of collapse and landslide in Wenchuan Earthquake provide rich sources for debris flows.In the rainy seasons of 2008,2009 and 2010,disasters of 11 debris flows gullies happened,esp.in the Donglinsi-Haihui Bridge.During the debris flow in Haihui,many bridges,houses,roads were destroyed.Based on field investigation and analysis,the relevant characteristics of debris flow are studied as：（1） the debris flows of earthquake-hit area have an increase frequency of outbreaks and different outbreak points and scale.（2） Most debris flows are viscous debris flows.（3）The debris flow ranges of activities are controlled by the rainfall and geomorphology.（4）There are different debris flow hazards,such as destroyed,deposition,buried and damming river.The earthquake-hit area in 2008,2009 and 2010,debris flow showed intense activity with strong activity time,possibly up to 5-10 years,even longer.Therefore,in the debris flow construction area,long-term prevention measures are introduced to prevent debris flow hazards.