Experimental And Numerical Studies On Dynamic Deformation Characteristics Of Fiber Reinforced Soil

The amount of abandoned sludge in China is huge and growing rapidly,and how to utilize it as a resource has always been a hot and difficult research topic.The fiber reinforced solidification technology improves soil through chemical and physical actions.The improved fiber reinforced solidified soil has high bearing capacity and resistance to deformation,and can be used as embankment filler.In practical engineering,fiber reinforced solidified soil is not only subjected to static loads,but also bears dynamic loads such as vehicles.Therefore,conducting research on the deformation characteristics of fiber reinforced solidified soil under dynamic loads is of great significance for its engineering applications.This study combines indoor experiments,numerical simulations,and theoretical analysis to focus on the dynamic deformation characteristics of fiber-reinforced solidified soil under vehicle loads.A deformation calculation method for fiber-reinforced solidified soil under long-term vehicle loads has been developed,which can provide theoretical reference for the application of fiber-reinforced solidified soil in practical engineering.The main research results are as follows:(1)Cement has a significant impact on the unconfined compressive strength of solidified soil in the early stage,mineral powder has a significant impact on the unconfined compressive strength of solidified soil in the later stage,and fly ash has a relatively small impact;Taking into account both cost and environmental factors,for muddy soil with a moisture content of 70%,the optimal dosage of solidification agent is 4% cement,4% mineral powder,and 1% fly ash.(2)The stress-strain curve of fiber-reinforced solidified soil shows a strain softening type,and its shear strength increases with the increase of confining pressure;The content of basalt fiber has a significant impact on the shear strength of silt solidified soil,with an optimal content of 1.2%;The amount of basalt fiber has a significant impact on the cohesion,but a smaller impact on the internal friction angle.(3)The cumulative plastic strain curve of fiber reinforced solidified soil exhibits three different forms;When the dynamic stress increases,the amplitude of cumulative plastic strain increases continuously;The greater the dynamic stress,the faster the cumulative plastic strain grows,and the growth rate of cumulative plastic strain is relatively high in the early stage,gradually decreasing with the increase of earthquake frequency,and finally tending towards 0;The changes in dynamic and static strength of fiber reinforced solidified soil with basalt fiber content are basically consistent.On this basis,a formula for predicting the dynamic strength of fiber-reinforced solidified soil was proposed and verified,with good fitting.(4)The fiber content will affect the magnitude of cumulative plastic strain under vehicle load,with an optimal content of 1.2%;The increase in dynamic stress caused by vehicle load will increase the cumulative plastic strain of the specimen;The faster the loading frequency,the smaller the final cumulative plastic strain;The longer the curing time of the sample,the smaller the final cumulative plastic strain under the same loading conditions;A calculation method for cumulative plastic strain of fiber reinforced solidified soil under different vehicle loads was established based on the SGompertz model.(5)Using ABAQUS software and random distribution theory,a numerical simulation method for fiber reinforced solidified soil was established and validated,which can consider the strength and quantity of fibers.This method can consider the effects of fiber content,mechanical properties,and other factors on the overall strength and deformation characteristics of fiber reinforced solidified soil,and can provide reference for subsequent research.