| As a new type of improved material,lignin fiber has the characteristics of economy,environmental protection and corrosion resistance.In the study of improved soil,the influence of lignin fiber on the engineering properties of soil was explored for the first time,aiming to provide reference for the research and promotion of improved materials.In this paper,Guiyang red clay is taken as the research object,considering the fiber content of lignin fiber under three curing ages(0d,10 d,30d)(0%,0.5%,1%,1.5%,2%,2.5%),3%)of the effect of the amount and three layers(one layer,two layers,three layers)reinforced and other influencing factors,through the physical test of density,specific gravity,boundary moisture content,triaxial compression test(CU),standard In the consolidation test,the effects of lignin fiber on the physical properties,strength and deformation characteristics of Guiyang red clay were studied.The one-dimensional consolidation creep characteristics were studied and analyzed.The main conclusions are as follows:(1)The test results show that the lignin fiber affects the physical properties of red clay to a certain extent,among which the density and specific gravity are the most obvious;the white ash component in the fiber increases the red clay powder content,and the whole red clay particle size is graded.The effect of the red clay is increased with the increase of the amount of the liquid.The overall increase of the liquid limit is greater than the plastic limit,and the plasticity of the red clay is enhanced to a certain extent.However,from the engineering point of view,the fiber is the whole red clay.The effect of physical properties is not obvious.(2)The cohesive force of red clay decreases first and then increases with decreasing amount.The internal friction angle is basically unchanged.The fiber content is 2% for the optimum amount,and the soil shear strength is The highest,when the lignin fiber content is small(less than 1%),the bite force between the fiber and the soil particle is smaller than that of the red clay,and the soil strength cannot be improved;the optimal dosage is the lignin fiber in each confining pressure.The residual strength of the lower soil has increased by at least 29%,which has certain reference value for engineering practice.(3)The stress-strain relationship curve of lignin fiber red clay is a typical strain hardening type.When the amount of each confining pressure is 2%,the peak value of the main stress difference is the largest,and after reaching the peak intensity,it still maintains a high residual.Strength;under the same stress difference condition,the strain of fiber reinforced soil is obviously smaller than that of natural red clay,and the fiber reinforcement effect is obvious.(4)Lignin fiber layered reinforced red clay,with the increase of the number of reinforced layers,the cohesive force shows a tendency to increase first and then decrease,and the internal friction angle of layered reinforced red clay and unreinforced red clay Compared with the change is not obvious,when the number of layers is one layer,the cohesion is the largest and the soil has the highest shear strength.When the confining pressure is low,the soil can maintain high residual strength;the higher the confining pressure,the more obvious the residual strength of the soil decreases.Generally speaking,the layered reinforcement method can not improve the strength and deformation of the soil.(5)The compressive modulus of lignin fiber red clay increases first and then decreases with the increase of fiber content,and reaches the maximum when the dosage is 2%.Under different pressure levels,lignin fiber can The compressive modulus of the soil is effectively increased;the strain of the lignin fiber red clay increases with the increase of the consolidation time and the consolidation pressure,and the consolidation pressure of each stage enters the stable creep stage after 60 minutes of application;Lignin fiber can effectively change the strain of red clay when it enters the stable creep stage. |
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