A Preliminary Study On The Disaster Chain Induced By Large Debris Flow In

This paper took Hongchungou debris flow as research object, and studied several aspects of Hongchungou debris flow in Wenchuan County in detail such as characteristics, intersection mechanism by the analysis of the data collection, site investigation and outdoor test, the factors influencing in river junction and the simulating calculation of dam break on barrier dam. The full text contents and results are as follows:(1) Through the survey about the main ditch of the "8.14" Hongchungou debris flow and other three branch ditch (Ganxigou, Dashuigou and Xindianzigou), found that the debris flow was composed by gravels and boulders mainly in the study area, which belong to the viscous debris flow with large stones. And it was concluded that the debris flow in the study area is easy to trigger at these conditions which provenance conditions, source water conditions and terrain conditions were met fully.(2) According to the basic characteristics of debris flow and flow junction, discussed intersection mechanism of debris flow at several aspects such as the intersection of debris flow movement way, the way of river scour and accumulation body. Found that in profile accumulation form, these way included submersible, pusher, resource accumulation and mixing were leading roles on debris flow; In plane accumulation form, river plugging, piled up, acting along with the flow and mixing were leading roles; Nevertheless, in the scour form of accumulation body of debris flow, lateral and bottom scouring played mainly roles. Thus, this paper proposed the master factors on the "8.14" Hongchungou debris flow.(3) Debris confluence physical simulation experiment. Main controlling factors of the impact of plugging river intersection Angle respectively, the velocity ratio and flow ratio, moisture content, a solid material into the remit total amount and the five experiments of blocking river pattern, respectively. Groups of experimental results and analysis summarized as:along with the debris flow convergence Angle, a into the increase of total solid content source material and so on for plugging river, the phenomena of and the main river and debris flow with the increase of flow rate ratio and velocity ratio is not conducive to debris flow blocking river; The influence of moisture content has a parabolic relationship, along with the increase of parameters for plugging Jiang Xian favorable and adverse direction development; Combined with the experimental results for many times, it is concluded that blocking river basic patterns:latent dam block, local congestion, completely blocked. In addition, the experimental calculation parameters and the characteristics of the debris flow gully data comparison shows that the experimental calculation results is consistent with the actual situation of debris flow gully.(4)The debris flow disaster chain simulation calculation and analysis. Landslides in the study area, for example, the induced debris flow disaster chain, including debris impact of peak flow, debris flow, landslide damming flood routing process) a detailed calculation and analysis. It is concluded that the study area mud-rock flow ditch mouth impact is very big, enough to instantly destroy the main river surrounding environment (such as vegetation, roads, Bridges, housing, etc.).Gradually expand dam model better reflect the dyke basic features, also with the actual dam flood peak flow fitting is very good, and the gradual dam model calculation of flow coefficient is0.32, reasonable computational time (ΔT=600s); Downstream of the dam crest to advance the process, the maximum flow of each section, parabolic relation with the maximum water depth and distance, namely with the increase of distance, first in a quick and then to slow decay, distance and time of arrival in each section and basic linear relationship.