The Experiment Research For The Formation Characteristics And Conditions Of Typical Rainstorm-induced Debrisflow In Wenchuan Earthquake Area

Rainstorm-induced debris flow has these characters, which are strong confidentiality, high potential hazard, suddenly outburst, no obvious omen, low frequency, serious harms, great scale, heavy disaster, etc. With the needs of economic construction development of the mountain area, and the continued deepen research of the rainstorm-induced debris flow disaster, an important aspect of disaster prevention and mitigation of rainstorm-induced debris flow—the research of the formation characteristics and conditions of rainstorm-induced debris flow, has attracted more attention. However, the formation of rainstorm-induced debris flow disaster is complex, and the research results achieved at present is far from meeting the requirements of disaster prevention and mitigation in the mountains area. The occurrence of 9.24 Beichuan rainstorm-induced debris flow shows that the rainstorm-induced debris flow in Wenchuan earthquake area has entered a new period of activity, the next 5-10 years ,the occurrence of rainstorm-induced debris flow in this region will become even more frequent. Therefore, we should reinforce the rainstorm-induced debris flow gully research in Wenchuan earthquake area, and study their formation characteristics and conditions, on this basis, actively implement debris flow forecast, which is very important and with practical significance.After investigating a typical representative debris flow gully in the field in Wenchuan earthquake area ,this paper has carried out a simulation experiment in indoor laboratory of rainstorm-induced debris flow, and made a certain research in such as characteristics and forming conditions of rainstorm-induced debris flow, through the analysis of the relevant data obtained by the indoor experiment of the rainstorm-induced debris flow, we obtained the relationship between the mean flow velocity , the superficial flow velocity , the discharge and the slope in the process of debris flow motion under the conditions of different gradient sections, from the surface of d50 particles start to the time of forming of debris flow. On this basic of the analysis of the indoor experimental data, this paper discussed the formation conditions of this typical representative rainstorm-induced debris flow, which lay a theoretical foundation for the forecast of formation conditions of rainstorm-induced debris flow. Through the data of the discharge obtained by the indoor experiment of the rainstorm-induced debris flow in the process of debris flow motion ,which under the conditions of different gradient sections, from the surface of d50 particles start to the time of forming of debris flow, this paper calculated the discharge condition during the rainstorm-induced debris flow was forming.According to the comparison between the experimental results and the formation characteristics data of the Xishanpo debris flow gully by the field survey, we can see that the parameters of the debris flow such as the discharge can meet the formation conditions which extrapolated by the experiment, the results calculated by the experiment is in line with formation conditions of the Xishanpo debris flow gully. During the contrast process between the experimental results and the formation discharge conditions of the Xishanpo debris flow gully by the field survey, this paper but also considered the characteristics during the motion of the Xishanpo debris flow, finally the comparison between the experimental results and the formation conditions data of the Xishanpo debris flow gully showed that the experimental results is in line with the actual situation of the Xishanpo debris flow, and this proved that the results of the experiment can be accurately for the foundation of preliminary forecast for the debris flow. This paper started from the relationship between the rainfall and the formation of debris flow, which due to rainstorm flood flow calculation, combined the debris flow forecast with the weather forecasting, as the conditions of the rainstorm-induced debris flow forecast, and based on which , this paper provided a certain basis for the method of the debris flow forecast , which considered the role of the rainfall intensity, duration, the results of the research can be applied to the initial forecast of identifying random rainstorm for debris flow danger, it will help government departments to strengthen the disaster forecast for the rainstorm-induced debris flow and make mass monitoring for debris flow disaster management and provided technical support for the establishment of effective disaster prevention and mitigation decision-making management system.