| The problem of water damage is an important obstacle to the construction of aeolian sand highways in the hinterland of the desert.Short-term heavy rainfall often causes roadbed void,slope collapse and slope failure.What kind of slope reinforcement and protection measures can be used to effectively solve this problem has always been a hot topic in the industry.Based on the field investigation of the Wuma Expressway project,this paper discusses the measures to reinforce the slope surface of the aeolian sand slope by using the slope soil covering technology,and studies the slope erosion damage characteristics of different slopes and different soil particle sizes under specific rainfall intensity.The protective effect of aeolian sand slope under the influence of multiple factors is evaluated by indoor model test and finite element simulation technology.The main conclusions are as follows:(1)Based on the Wuma highway project,the physical and mechanical properties of aeolian sand such as particle gradation,microstructure characteristics and compactness were measured.The results show that the particle size of aeolian sand is mainly distributed in 0.075～0.5mm,the non-uniformity coefficient C_u is between 1.50～1.62,and the curvature coefficient C_c is between0.78～0.8.The particles are loose at the macro level,and the microscopic performance is a typical contact pore structure.There is no salt cement or clay between the particles;the standard dry density is 1.69 g/cm~3,and the natural moisture content is 1.5%～2.0%,which lays a foundation for subgrade filling and engineering application in aeolian sand field.(2)Through the indoor model test,the law of sediment yield on the slope under the condition of 0.091 mm/min rainfall intensity was analyzed.When the slope was 13°and 25°,the sediment yield was 1 to 2mm slope,3 to 5mm slope and 6 to 9mm slope.When the slope was37°,the sediment yield was 6 to 9mm slope,1 to 2mm slope and 3 to 5mm slope.Therefore,when the slope is 13°,the particle size is 1 to 2mm or 3 to 5mm,when the slope is 25°,the particle size is 1 to 2mm,and when the slope is 37°,the particle size is 6 to 9mm.(3)Through the indoor model test,the relationship between sediment yield and runoff rate,average flow rate under the condition of 0.091 mm/min rainfall intensity is analyzed.It is concluded that the relationship between sediment yield and runoff rate,average flow rate and their interaction is linear.Under the experimental conditions,the critical runoff rate of sediment yield is 0.051 L/min,and the critical average flow rate is 0.017 m/s.The critical value can be used to predict the damage degree of aeolian sand slope after rainfalll erosion,and to guide the soil erosion control of aeolian sand slope under the condition of short-term heavy rainfall,so as to reduce the sediment yield of slope.(4)Through the finite element simulation,the rainfall infiltration law of the aeolian sand slope under the rainfall intensity of 0.8 mm/min is analyzed.It is concluded that the continuous infiltration of rainfall leads to the overall upward trend of the pore pressure of the slope,and the pore pressure distribution decreases from the surface of the slope to the inside of the slope.The growth rate and variation range of the pore pressure on the surface of the slope are always greater than the change of the pore pressure inside the slope.High-intensity short-term rainfall will form a local high water cut area on the outer surface of the slope soil and gradually penetrate into the slope soil.The water content and saturation gradually change,and the change law of saturation is basically the same as that of pore pressure.(5)Through the artificial condition,the influence of overburden reinforcement measures on the stability of aeolian sand slope under 0.8 mm/min rainfall intensity is analyzed.After the reinforcement of 3 to 5 mm overburden and 6 to 9 mm overburden,the maximum horizontal displacement is reduced,which are reduced by 37%and 70%respectively.The slope safety factor is 9%and 15%higher than that of the uncovered soil.Therefore,the larger the particle size of the overburden is,the higher the slope safety factor is,and the better the slope protection effect will be. |
