The Debris Flow Characteristics And The Development Trend Forecast Of Xingfu Gully In Wolong

Xingfu gully is a typical valley debris flow gully, with has happened many times massive mudslides in the geological history. After the "5.12" earthquake, gully domain has produce a large amount of debris content source, and two large debris flow happened in 2008 and 2013, it may happen massive mudslides again in the near future, serious threat to the ditch within Panda Research Protection Center, the Panda wild training raised field and the residents of gengda township at the ditch, S303 province road of security, so the development characteristic, movement characteristics, development trend of the Xingfu gully, to guide the engineering design, that has a certain practical significance.The thesis has researched the formation condition, the origin of the ancient landslide evolution history and earthquake debris flow activity of Xingfu gully,based on the geology condition and the system researching the development of debris flow characteristics. simulated the debris flow movement in the channel of "7.10" debris flow and under P = 1% rainstorm frequency,on this basis to predict the development trend of debris flow, put forward suggestions for the project management of debris flow. Made the following main understanding:(1)Xingfu gully is a debris flow gully with large drainage area and the development of branch gully. After "5.12" earthquake, trench added a lot of provenance debris flow, this trench source total reserves of about 1377.32 ×104m3, reserves about 114.80×104m3, in case of heavy rain, easy to form a branch channel and main channel of debris flow.(2) Xingfu gully is an old debris flow gully, periods of geological history happened at least five massive mudslides, each phase of the debris flow deposit is set of fan to pile up. According to the characters of the development of the ancient debris flow, speculated that the ancient debris flow activities has experienced 5 cycle from the active to the intermittent, and outbreaks of debris flow and active period. Ancient debris flow deposits dominated by magmatic rocks, accordingly, suggesting that the source to ditch the main road on the left bank of the magmatic rock distribution area, as the Maowen fault occur 5 times large magnitude ancient earthquake.(3) The scale of the modern debris flow in Xingfu gully is small relative to the ancient debris flow, and its developmental features are similar to that of the ancient debris flow. Before "5.12" earthquake, debris flow is not active, only in June 1964 and 1992 July outbreak two times. After the earthquake, the debris flow into an active period, has in June 2008 and July 2013 outbreak two times larger debris flow, from low-frequency debris flow before the earthquake change to high frequency and the scale is also increasing. After the earthquake, debris flow of the main channel for subaerial debris flow, mainly in trench relatively wide slow and crossing ditch accumulation, but due to the accumulation of a smaller range of the principal channel crossing, the packing fan development; the debris flow of branch gully is viscous debris flow, mainly in the branch gully accumulation, into the main channel in accumulation.(4) Using computational fluid dynamics software CFX to simulate the middle and lower reaches of main ditch and three large branch channel downstream of the branch ditch in Xingfu gully. The simulation results of the "7.10" debris flow velocity field, of the gully bed shear stress and compressive force field, and the mud marks survey method to calculate the "7.10" debris flow high degree of coincidence. Thus, the simulation results of the debris flow at P=1% rainstorm frequency can provide a reference for the debris flow control engineering design.(5) Based on the ancient mud rock flow history evolution causes and modern debris flow development features of Xingfu gully, and combinating of the quantitative calculation, speculated that the debris flow stimulating of earthquake rainfall fell about 2/3 after the earthquake, the debris flow activity is still active in the next 10 years, branch gully is more easily outbreak mudslides to the main gully. In early adequate rainfall under the premise, the same day rainfall reached 105 mm, it can stimulate once in 100 years of debris flow, the size of approximately 15.08 ×104m3. Through the qualitative analysis and the empirical formula to modify the quantitative calculation shows that when happiness the debris flow in 100 years of the worst outbreaks, resulting in their Yuzixi river completely blocked off the possibility of a larger. Finally, giving the combine comprehensive control measures, such as Block engineering, Lead Engineering, bioengineering.