TYPICAL DEBRIS FLOW BLOCKING RIVER PATTERN ANALYSIS BASED ON THE NUMERICAL SIMULATION

A large number of landslides were produced in the Minjiang River near the epicenter by Wenchuan earthquake. With extreme rainfall weather, debris flows gradually become the main secondary disasters after earthquake. On 3th July 2011,debris flow occurred in Gaojia debris flow under rainstorm condition, destroying woodland, burying old road, almost blocking Minjiang River, and affecting seriously the reconstruction of the tunnel entrance. In order to decrease the losses of blocking river by debris flow in intense seismic area, this article selects Gaojia debris flow in Minjiang river as the research object. Numerical simulation was adopt to simulate Gaojia debris flow movement under different rainfall intensity(5 years, 20 years, 50 years, 100 years), and further analysis the different levels of blocking river pattern. The numerical simulation accuracy can reach 81.4%by field validation. The results show that there are no loose material run out under the condition of 5years rainfall intensity, failed to plugging river in 20 years rainfall intensity, partially blocking river in 20 years rainfall intensity, and completely blocking the river under the condition of 100 years rainfall intensity.