Abstract
Slope failure triggered by soil erosion under rainfall remains one of the most difficult problems in geotechnical engineering. Slope protection with planting vegetation can be used to reinforce the soil and stabilize the slope, but the early collapse of the planting soil before the complete growth of plants becomes a major issue for this method. This paper has proposed a composite soil treatment and slope protection method using the geocell structures and the wheat straw reinforcement. The geocell structures improve the stability of the planting soil and provide a stable and fixed environment for the vegetation, while the wheat straw reinforces the soil and also increases the fertility. The authors have performed a total of 9 experiments in this work that are classified into three groups, i.e., the unsupported slopes, the geocell reinforced, and the geocell and wheat straw composite reinforced with a consideration of three different rainfall intensities. The progressive slope failure development during the rainfall was assessed, as well as the soil erosion, the slope displacement, and the water content. The results show that the slope failure increases as the rainfall continues, and the soil degradation increases with the intensity of rainfall. The soil treatment using geocell improves the slope stability, but the geocell and wheat straw composite reinforcement has the best erosion control and slope protection.
Highlights
Shallow slope failure refers to a superficial removal of vegetation cover and topsoil, which is a common problem typically observed in areas of hilly or mountainous terrain, engineered road, and embankments. e shallow slope failure can be addressed as the shallow landslide and shallow soil erosion
Other advantages such as a short construction period and Advances in Civil Engineering low maintenance charges can be identified for this environmentally-friendly and ecologically-friendly method of slope protection [1,2,3,4]. e disadvantage, on the other hand, is that the soil for planting vegetation on the surface of the slope may collapse before the plants start to stabilize the slope at fully grown. e collapse of the planting soil occurs especially at the early stage of construction under a heavy rainfall. e failure of the soil reinforcement re-exposes the original slope to the rainfall, which increases the risk of landslide
At the rainfall intensity of 100 mm/h, the amount of soil erosion for the unsupported and geocell-reinforced slopes is both raised to an extremely high level at 22452.7 g and 20928.3 g, respectively. e composite reinforced slope sees an 82% of reduction as compared to the unsupported model, indicating that the geocell and wheat straw composite treatment is more effective in protecting the slope and preventing the soil erosion especially under a heavy rainfall
Summary
Shallow slope failure refers to a superficial removal of vegetation cover and topsoil, which is a common problem typically observed in areas of hilly or mountainous terrain, engineered road, and embankments. e shallow slope failure can be addressed as the shallow landslide and shallow soil erosion. E advantages for the composite treatment are listed as follows: (1) the strawreinforced soil presents larger cohesion and internal angles than the original untreated soil; the shear strength is enhanced with better performance against the rainfall erosion; (2) since the shallow soil at the top layer of the slope is reinforced with the wheat straw, the permeability of the soil is reduced with less pores existed, which slows down the penetration of rain water and improves the slope stability; (3) by mixing the straw with the soil, the weight of straw gradually decreases as microorganisms grow and break down the straw. Is paper has proposed a composite soil treatment method for slope protection using the geocell structures and the wheat straw. e geocells are buried into the planting soil, and the wheat straw is mixed with the soil for reinforcement at the shallow depth. e advantages for the composite treatment are listed as follows: (1) the strawreinforced soil presents larger cohesion and internal angles than the original untreated soil; the shear strength is enhanced with better performance against the rainfall erosion; (2) since the shallow soil at the top layer of the slope is reinforced with the wheat straw, the permeability of the soil is reduced with less pores existed, which slows down the penetration of rain water and improves the slope stability; (3) by mixing the straw with the soil, the weight of straw gradually decreases as microorganisms grow and break down the straw. e decomposition of the wheat straw increases the fertility by providing nitrogen or other nutrients in soil and fosters the growth of vegetation planting on the slope. e root system of the plants in return reinforces the geocell-reinforced soil, which further improves the slope stability
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