Analyses of Characteristic Values for Sanyanyu Debris Flow in Zhouqu County on August 8,2010

Through investigation on the giant debris flow hazards in Zhouqu County Gansu Province on August 8,2010,the characteristic values of the statistics and dynamics on the debris flow are analyzed.The results are as follows: Unit weight of the debris flow in Sanyanyu valley lies between 2.0 t/m3 to 2.15t/m3.So,sanyanyu debris flow belongs to viscous debris flow.Development characteristics of the branch gully(including Dayanyu gully and Xiaoyanyu gully) appear as large gradient and narrow valley bottom,compared to the main gully,the debris flow velocity is more rapid in branch valley and the maximum velocity is 9.2m/s.The debris flow amass enormous energy in flowing zone.The peak discharge of debris flow appear in interjunction of Dayanyu valley and Xiaoyanyu valley,the maximum discharge is 1 830 m3/s.The most volume of once flow is 1.52×106m3,and the debris flow in Sanyanyu valley belongs to giant debris flow hazards.The maximum impulsive force of the Sanyanyu valley debris flow are 245kPa and located on the section of the Sanyanyu valley outlet.The maximum particle diameter of block stone is 11.2m in debris fans.The velocity of the block stone in debris flow is up to15.06m/s.the analytical results of characteristic values for Sanyanyu debris flow are very important,it can provide design criteria for reconstruction projects after the disaster.