INTERCEPTION EFFECT OF STREAM VALLEY BENDS TO ROCK FALL BLOCKS IN WENCHUAN EARTHQUAKE

On the basis of the investigation and the statistics on site,this paper studies the distribution characters of the whole and different volume groups' rockfall of more than 200 blocks along the bended valley at Donghekou in Qinchuan town.The rockfalls happened during the 2008 Wenchuan Earthquake.The concept of rock blocks interception rate are given on the basis of statistical information.Then,the interception effect of the turning point and the rock blocks' distribution in the valley are analysed quantitatively from the point of the rock block number and the rock block volume.The conclusions are given as follows: the valley bend has the positive effect on controlling the following of the rockfall blocks; the larger the rock block,the bigger possibility intercepted at the point.From the view of the number,the bend turning point near the rockfall resource intercepted more rock blocks than that near the foot of the mountain.The method and the conclusions give the support to research bended valley and its turning point controlling the migration of the rockfall deposits,and also give some reference for preventing the rockfall hazards.