| Slope protection can effectively reduce soil erosion on the loess surface and improve the stability of loess slopes.After traditional physical reinforcement and biological reinforcement,there are generally problems such as stiff landscape and greater restrictions on vegetation and water sources,while traditional chemical reinforcement materials generally have problems of excessive environmental pollution and durability.Under long-term rainfall conditions,the slope is prone to peeling,falling off,and landslides,which limits the application of reinforcement technology.In this paper,two curing agents,calcium lignosulfonate(referred to as wood calcium)and basalt fiber,were selected,and the direct shear test,disintegration test,penetration test and loess collapsibility test were carried out.The effects of different factors on the mechanical properties,hydraulic properties and deformation characteristics of loess were investigated experimentally.These factors include the amount of single curing agent,the mixing ratio of curing agent,curing age,degree of compaction and moisture content.A comprehensive evaluation method was used to obtain the optimal ratio of the two curing agents,and based on this,a rainfall scouring test was carried out to test the protective effect.The research results showed that:(1)Basalt fiber can effectively improve the shear strength of loess and reduce the collapsibility coefficient.Compared with the plain soil,the fiber-reinforced soil with 0.4%content increased its cohesion and friction angle by 201.6% and 18.8%,respectively.When the vertical pressure is 1000 k Pa,the collapsibility coefficient decreases by 59.5%.However,the addition of fibers makes the disintegration resistance of the soil worse and the permeability coefficient increases.The 1.5% content of wood calcium has the best comprehensive improvement effect.It is the best content.It has a limited impact on the shear strength,but reduces the permeability coefficient and collapsibility coefficient,and greatly improves the water stability of loess.Compared with the plain soil,the average disintegration rate of the solidified soil was reduced by 4.28 times.(2)The combination of the two curing agents can greatly improve the strength,water stability and anti-deformation properties of loess,and 1.5% calcium lignosulfonate + 0.4%basalt fiber is the optimal ratio.The shear strength of the soil samples under the optimal ratio increased with the increase of the curing age,and the soil did not disintegrate after curing for 7 days.With the increase of water content,the disintegration resistance of the solidified soil is enhanced,and 17% is an obvious dividing point.With the increase of compaction degree,the average disintegration rate of soil gradually decreased and the disintegration time was prolonged.(3)Calcium lignosulfonate-basalt fiber has obvious protective effect on slope surface.Compared with the unprotected slope,the pit generation time of the protected slope retreated under the action of rainfall erosion,and the number of pits decreased.The slope is no longer damaged by gravity erosion,and the amount of sediment scour is reduced from2504.56 g to 5.43 g.During the rainfall process of the protective slope,the peak value of the pore water pressure sensor becomes lower,the fluctuation amplitude becomes smaller,and the dissipation rate is slower.At the end of the rainfall,the moisture content of sensors w1,w2 and w3 decreased from 32.33%,29.19% and 31.45% of the unprotected slope to 31.81%,28.15% and 28.03%.(4)In the composite modification,wood calcium greatly improved the water stability of loess mainly by filling pores and binding soil particles.Basalt fibers form a spatial structure in the soil through the mechanical action of the fiber-soil interface,which can strengthen the connection between soil particles,thereby greatly enhancing the mechanical properties of loess. |
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