地震灾区新建蒲虹公路弃土泥石流成灾特征与防治建议

CHARACTERISTICS AND PREVENTION STRATEGY OF SPOIL DEBRIS FLOW ALONG NEWLY-BUILT PUYANG-HONGKOU HIGHWAY IN EARTHQUAKE-STRICKEN AREA

蒲虹公路是地震灾区的一条灾后新建公路。公路外边坡堆放有大量的弃土,在强降雨的作用下易转化为泥石流。此类现象受到研究者的关注。本文通过对弃土场的分布、组成及成灾特征的研究,提出了科学合理的处理方法。弃土泥石流形成模式包括:(1)沟道内弃土场在沟道洪水侵蚀作用下产生泥石流或土体溜滑形成泥石流;(2)坡面上弃土场滑动,表面液化形成局部坡面泥石流;(3)沟道两侧弃土场的基脚被侵蚀,形成滑坡堵河后溃决形成泥石流。弃土泥石流的成灾特征主要为弃土泥石流翻越挡墙或摧毁挡墙,堵塞涵洞或排水口,淤埋公路,威胁居民点等,它的处置需要特别注意排水,并平整压实,恢复生态。

Debris flows induced by the Wenchuan Earthquake greatly affect the reconstruction in earthquake-stricken area.Puyang-Hongkou highway is one newly-built in the earthquake-stricken area.A lot of discarding soil is piled up on the slope,which may be transferred into debris flow under heavy rains.This phenomenon and hazards are very attractive for researchers.In this paper,the distribution of the sites of discarding soil,the formation and hazards characteristics and control measures are studied.In conclusion,the debris flows are triggered by 3 types of model：（1） the discarded soil in the gullies is triggered by flood or liquefied into debris flows;（2） The discarded soil landslides and the soil on surface liquefied partially into debris flow;（3） the foot of discarded soil at both sides of gullies is eroded and the soil collapses to block,and then bursts to form debris flows.The hazards appear to be turning over or destroy the wall,blocking the culvert,covering the road and endangering the residents.When settling down this problem,it is important to drain,flat the surface and plant trees.