Abstract
In view of the failure characteristics of rainfall erosion and imbricate layered sliding of silt subgrade slopes, this paper proposes a slope surface protection technology that is a composite protection layer that combines basalt fibre for reinforcing soil and polyacrylamide for solidifying soil. The anti-infiltration and anti-erosion performances of these proposed composite layers were systematically investigated through the finite element and discrete element numerical simulation methods. Based on the optimum proportions of polyacrylamide and basalt fibre found in a series of mechanical experiments, Geo-studio software was used to simulate numerical tests of rainfall infiltration of the silt subgrade slope, and the variation laws of volumetric water content and pore water pressure at the characteristic points and the selected sections of the slope were discussed. In addition, the PFC2D particle flow program was used to develop numerical tests on the slope erosion process of the composite layers and to analyze the degree of soil erosion during the process. The influences of layer thickness on infiltration and erosion were considered. In conclusion, the results indicate that the composite layers can effectively improve the anti-infiltration and anti-erosion performances of the silt subgrade slope. This highlights that the thickness of composite layers mixed with basalt fibre can satisfy the design parameter requirements for anti-erosion performance.
Highlights
Silt consists of Quaternary fluvial-lacustrine or aeolian sediments, which are widely distributed in the lower course of the Yellow River, Huaihe River and Haihe River in China
Silt stabilization research and practice have made good progress (Indraratna et al, 2012; Kavitha et al, 2015), but there is still much room for improvement, including stabilization effectiveness and cost (Marto et al, 2014; Suksiripattanapong, et al, 2015; Guo et al, 2020b; Wang, et al, 2021b).Based on a new slope protection system of three composite layers [silt and polyacrylamide (SP layer); silt, basalt fibre and polyacrylamide (SBP layer); and silt and basalt fibre (SB layer)], the aim of this study is to explore the anti-infiltration and anti-erosion performances of the composite layers and discuss the thicknesses of the SP, SBP and SB layers by means of mechanical and erosional experiments and the rainfall infiltration and erosion of numerical simulation
The subgrade slope with composite protection layers rises to the saturated volumetric water content of 0.46 only in the SP mixed layer, and the area of variable volumetric water content occupies 27% of the slope
Summary
Silt consists of Quaternary fluvial-lacustrine or aeolian sediments, which are widely distributed in the lower course of the Yellow River, Huaihe River and Haihe River in China. Soil detachment by raindrops is expressed as a Performance of Slopes Composite Layers function of their kinetic energy, which depends on the quantity of rain and the intensity of the showers. Other methods rely on physical and mathematical models to quantify soil erosion (Meyer and Wischmeier, 1969; Cochrane and Flanagan, 2001; Kang et al, 2019; Fan et al, 2020). These methods, when they are well established, are an indispensable tool in choosing antierosion practices that allow for limiting runoff volumes and better controlling flow water on the slope scale
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