Research On The Formation Mechanism And Treatment Measurements Of The Pengjiapo Rockslide-debris Flow

Rockslide-debris flow is a special kind of geological disasters made by the rock slope collapsing. The failure process of the slope can be divided into two segments including both the rockslide along the weak discontinuion on the upper slope and the rockfall of the broken rock mass on the lower slope.This paper elucidated the characteristics of Pengjiapo rockslide-debris flow at Wangcang County, Sichuan. It emphasized the formation mechanism of the collapse body, figured out the failure mode of the rockslide-debris flow and analyzed the stability of the collapse body. Based on this, an effective emergency treatment measurements was brought out and verified by using numerical simulation method. The main achievements are as follows:(1) The total volume of Pengjiapo rockslide debris was 503200 m3. On March 22,2011,392000 m3 of collapsed mass narrowed the channel of the Wulang river and blocked Wuquan road. About 111200 m3 of residues of rock mass on the slope was instable due to the rock fracture enlarging. Large-scale collapse may happen at any time. So emergency treatment measurements is necessary and urgent.(2) Two main facters, i.e., rainfall infiltration and mining activities, casued the rockslide-debris flow.(3) Stability evaluation for the endangerous rock masses showed that Wyl rock mass, Wy2 rock mass, and Wy3 rock mass were unstable state under the action of external force such as heavy rain storms and earthquakes.(4) Emergency treatment measurement, i.e., stable pile+anchor+clean up the dangerous rock mass+retaining wall+cutting slope, is proposed.