谷坊在泥石流防治中的作用——以云南蒋家沟2条支沟的对比为例

FUNCTIONS OF CHECK DAM AGAINST DEBRIS FLOW:COMPARISON OF TWO WATERSHEDS OF JIANGJIA GULLY,YUNNAN,CHINA

泥石流灾害严重威胁其影响区人民的生命和财产安全,但是泥石流灾害可以通过诸如控制侵蚀等工程措施来预防或者减轻。谷坊正是能够在泥石流形成区对泥石流灾害进行有效防治的工程措施之一。在野外实地调查的基础上,运用构造地质、工程地质、岩土力学等理论和方法,对比云南蒋家沟泥石流的2个主要支沟——门前沟(有谷坊布设)和多照沟(没有谷坊布设)在沟床纵坡降、沟谷两侧斜坡稳定性及泥石流侵蚀速率等3个方面的差异,来说明谷坊工程能够有效抬高泥石流侵蚀基准面,降低泥石流沟谷回淤段沟床纵坡及由此带来的泥石流流速的降低和能量的耗散,固定沟床、稳定岸坡、促进植被生长,最终达到防治泥石流的目的。此外,还讨论了谷坊设计时需要注意的几点问题。

Debris flow activity has recently caused serious property damage as well as loss of life in Yunnan, Southwest China. Moreover, ground failure caused by debris flow needs a long time to be recovered. The hazards of debris flow can be prevented or released by some engineering countermeasures such as erosion control. The check dam is one of the most effective structures to control the debris flow in the original area. Based on the examination of Architectonic geology, engineering geology, rock mechanics and remote sensing geology, two major tributary gullies（one with check dams but the other without） of Jiangjia Gully in Yunnan Province, are compared in three aspects （channel longitudinal gradient, stability of lateral slopes and trailing edge of channel, soil erosion by debris flow） to prove that check dam or check dam series can： （1） effectively uplift the basic level of erosion of debris-flow channel; （2） reduce the longitudinal gradient of the debris-flow channel, and accordingly velocity slowed down and energy dissipated; （3） fix the channel and stabilize the slope so as to facilitate or restore the growth of the vegetation. In addition, several problems, needed to be taken into account during the design of check dam, are also discussed.