Study On The Basin System Evolution Of Lamaxigou Wenwupo And Its Impact On The Project

Ya'an～Shimian～Lugu expressway is the key project of western Chinese current construction, which is planed and constructed. It is a four-lane highway all standards and the design speed of 80 km/h. The topographical and geologic conditions are very complicated. The Lamaxigou Wenwupo Xigeda-stratum is poor nature of engineering geology. A number of gullies were formed in the slope long-term water erosion. The gully has a longitudinal profile cutting depth of 30 to 40 m. It is a loose and poor stability in the side of the gully. It cuts easily instability in the process of erosion under the bed in the ditch. And there is a yearly to the groove and the first expansion of cross-strait ditch. This paper studies Lamaxigou Wenwupo evolution of valley system and to make quantitative evaluation, in order to ensure the Yalu expressway Lamaxigou Wenwupo's safe construction and work to provide a scientific basis.First of all, it is analyzed the impact of forming the background of geo-environmental conditions of Lamaxigou basin in this thesis. Rainfall runoff factors, geological physiognomy factors (lithology, structure and physiognomy, etc.), conditions of the physiognomy (gradient, slope length, slope shape, gully vertical slope, drainage area, the gully density, modulus of soil erosion, vegetation, etc.) and man-made factors are analyzed to find controlling factors for fathering erosion evolvement of this valley system to provide a scientific basis.Secondly, in the thesis it is elaborated on the concept of valley erosion, and thoroughly discussed the valley erosion system, and then analysisd of the valley erosion evolution of different types and characteristics of the formation. In this thesis it is applied strahler method, altitude integral method, information entropy method, and erosion integral method to compare, trending to predict the development of the main channel and the lesser channel of Lamaxigou.Filling pressure and repairing the barrage will change the channel of the local erosion base level, clearly impact the erosion of the original channel, the paper analyzes the natural siltation of no repairing the barrage, the gully siltation of repairing the barrage, the gully siltation of filling pressure and repairing the barrage, educing the three conditions trending of siltation at a certain period and preventive measures.Slope evolution is a natural historical process, its evolution process is also form a low grade balance system to an advanced balance system. It is analysised the slope evolution of failure mode, influencing factors and effect on the engineering, for providing corresponding basis of engineering design, construction and operation.