The Study on Numerical Simulation of Debris Flow Disaster Prevention Engineering Effect in Hongchun Gully, Sichuan Province

The study area Hongchun basin is located in the northeast side of Yingxiu Town, which is the 2008.5.12 Wenchuan earthquake epicenter. It is also located on the left bank of the Minjiang River. The ditch and valley pattern is approximate a sector and its area is 5.35 km 2 . The highest point is located in Xin Dian Zi Gou’s source; the elevation is 2162.2 m; Mizoguchi and Minjiang River intersection height is 881 m; relative elevation is 1288.2 m; channel longitudinal is 3.6 km; average longitudinal gradient of gully is 357.8 per thousand. It was found in the study that after the Hongchun gully disaster prevention project completed, it has broken twice debris flow in the design condition and once debris flow exceeding the design condition. In order to reasonably judge the effect of the project, we compared the simulation results with the actual operation results of the project. So in the numerical simulation of this article, we selected 2 representative recurrence periods of frequencies (p = 2%, p = 1%) to simulate. At the same time, according to the monitoring data of different sections and by setting up reasonable water gathering point positions in the simulation process, the disaster prevention project is divided into several sections for numerical simulation in this article. The numerical simulation results show that, in the design condition (p = 2%), the Hongchun gully disaster prevention engineering effect is remarkable, and over the design condition (p = 1%) the effect is also good.