平武县兴坪沟泥石流特征及其工程防治效果分析

FEATURES OF DEBRIS FLOWS AND THEIR ENGINEERING CONTROL EFFECTS AT XINPING GULLY OF PINGWU COUNTY

地震对地质环境的改变,产生的地质灾害效应会在5~10a或者更长的时间显现,汶川地震前后平武县发育泥石流数变化较大。根据多次现场调查,收集分析近8a的各类资料,对平武县地震前后发育泥石流情况及特征做了分析对比研究,对兴坪沟泥石流的基本特征、形成机制、近年来的发展演化情况以及工程防治效果进行详细分析,得出:(1)平武县境内因汶川地震诱发的泥石流灾害85%左右在地震后的5a内趋于稳定不再存在安全隐患;(2)兴坪沟因其物源极为丰富、主沟纵坡降较小、流域面积较大、支沟众多等特征目前还存在较大安全隐患;(3)兴坪沟泥石流防治工程效果良好;(4)下一步防治建议:在大沙坝段(距沟口1.1km处)修建单边防护堤,及时对郑家山滑坡进行工程治理,加强物源区耕地、弃渣管理,保护汇水区植被。

An earthquake can change the geological environment and show the geohazard effect within 5 to 10 years or even longer. The development numbers of debris flows in Pingwu County change a lot before and after Wenchuan earthquake. According to a series of investigation,by collecting and analyzing all kinds of data in the past 8 years,this paper tries to do a comparative research of the development situation and characteristics of debris flows before and after the earthquake in Pingwu County. It analyzes the basic features and debris flow mechanism and the evolution in recent years and engineering control effects. Then it finally gets the following conclusions.（ 1） About85% debris flow disasters caused by the Wenchuan earthquake in Pingwu County are stable and have no potential safety hazard within 5 years after the earthquake.（ 2） Because of its extremely rich source,the small main channel of longitudinal slope,the large watershed area and the large number of branches,there is still big debris flow risk in Xingping ditch.（ 3） The effect of debris flow prevention engineering in Xingping ditch is good.（ 4） Prevention and control recommendations are to build an unilateral protection embankment in the Dasha dam（ from entrance ofthe ditch 1. 1km） and to stabilize Zhengjiashan Landslide.Engineering management in time,in order to strengthen the management of the provenance farmland and waste slag and protect the catchment vegetation.