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

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) About 85% 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 of the 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.