Research On Sandy Soil Slope Erosion Of No.1 National Highway Of The Republic Of Congo

With the implementation of China's "going out" strategy,more and more Chinese enterprises participated in the international project.Congo(Brazzaville)No.1 national highway project was a key project in China aided in Africa.Because of the complexity of the highway engineering geological conditions,which sandy soil is widely distributed,brought certain difficulty for road construction.Compared with other soil,sandy soil is more prone to erosion and destruction in the condition of rainfall.At present,domestic and foreign scholars on the study of slope erosion damage is still insufficient.There is no more complete theory to guide the practice of engineering,so the issue needs further study.1.The geological survey of Congo(Brazzaville)No.1 national highway was summarized.The distribution of sandy soil in the area,the physical and mechanical properties of sand(such as soil particle size distribution,natural water content,natural angle of repose,permeability and shear strength of sand)and the characteristics of rainfall were studied in detail.These results provide data support for the design and theoretical analysis of laboratory experiments.2.The current research results of soil hydraulic erosion theory were summarized systematically,and the related theory of slope erosion occurrence condition,critical gradient for erosion and slope erosion quality was studied.Based on the Manning formula and the theory of the incipient velocity of soil particles under the water,the criteria for judging the occurrence condition of slope erosion was innovated;According to the stress condition of the soil particles on the slope,the formula of the critical slope gradient was derived;By using the energy method,slope erosion quality formula was established,and the sensitivity of slope angle,slope height and rainfall intensity on slope erosion was analyzed.Through theoretical study,it provided a theoretical basis for the design of the model test of sandy soil slope erosion;besides,the results of numerical calculation and the test results can be verified by each other.3.Based on the engineering geological characteristics of Congo(Brazzaville)and the model similarity theory,the model test of slope erosion was designed.Through the combination of different slope angle,slope height and rainfall intensity,the influence of these three factors on the erosion intensity was discussed,and the amount of erosion under different conditions was obtained.The slope erosion process and mechanism of erosion was studied,especially for further understanding of rill erosion of the origin,development and sediment transport;besides,the erosion process was described in detail.4.According to the research of the slope erosion occurring conditions and slope erosion quality,redesigned the erosion rules of cellular automata,initially established the form of damage simulation of rill erosion.Through CA simulation,the runoff data of the slope at different time was obtained;Using MATLAB platform to draw the three-dimensional shape of the slope,the simulation results was compared with the actual slope erosion shape to do a more intuitive understanding of the formation process of runoff;The elevation of the slope at different time periods was extracted for the preliminary exploration of the amount of erosion predicted by computer software.