ANALYSIS ON THE MOVEMENT CHARATERISTICS OF ROLLING ROCK ON SLOPE CAUSED BY INTENSITIVE EARTHQUAKE

Wenchuan Earthquake,with high intensity and long period,caused masses of rolling rocks which derived from block stones of rock slopes divided by structure faces and big size corestones of soil slope.The block stones are projected with initial speeds.Their movements on slope surfaces are the combination of sliding,rolling and jumping.Based on the field investigation,this paper chooses two typical unsteady slopes caused by the earthquake to study movement characters of rolling rocks.Three findings are as follows.(1)The more the rolling rocks have equal three dimensions in length,width,and height,the farther the rock movement distance.But for platy rolling rocks,if their narrow side touchdown firstly,and collide elasticcally,they will jump at a high speed and move long-distance; (2)At the 1/2 height of slope surface or higher,rolling rock movement is sliding,rolling mainly.At the lower positions,it is jumping-rolling,jumping-sliding; (3)Big size(mass)rolling rocks mostly stay at the first touchdown or the wide gently areas at the slope toe areas.The way to consume energy is friction or collision disintegration,in which the ratio of platform block is 54% and trees(shrub) is 12%. By inversion,renew coefficient Rn and Tangentially renew coefficient Rt are obtained.For the bare bedrocks,Rn=0.3 and Rt=0.6. For the overlay,Rn=0.2and Rt=0.8.For moving rolling rocks,their bounce heights are between 0.49~3.10m.The ratio of the maximum rolling height and the farthest movement distance is 1/2.