Study On Mechanical Properties Of Guilin Red Clay Modified By Basalt Fiber

As a unique regional soil,red clay is widely distributed,covering over 30% of China’s land.Under the background of the grand capital construction era,there are higher requirements on the mechanical properties of red clay.Numerous laboratory experiments have proved that adding fibre and additive into the soil can improve soil strength,so extensive research has been conducted on fibre-reinforced soil.Fibre reinforcement is a soil improvement technology that can add dispersed fibre wires into the soil evenly to improve soil’s mechanical properties.In this paper,basalt fibre is adopted as the modified material to investigate its effect on the mechanical properties of red clay.As a natural green inorganic fibre,Basalt fibre’s chemical composition is similar to that of soil.Adding basalt fibre into the soil does not increase chemical elements.At the same time,the improved soil can be reversible.In this paper,basalt fibres were evenly dispersed as filaments into red clay.The following conclusions were drawn by direct shear test,standard consolidation test,unconfined compressive strength test,shrinkage test,fracture test and SEM test,taking dry density and mixing rate as variables.(1)Through the direct shear test and unconfined compressive strength test to compare basalt fibre modified red clay with plain red clay,the effect of basalt fibre mixed with dry density on the strength characteristics of basalt fibre modified red clay was analyzed.The results indicate that the strength of basalt fibre modified red clay increases with the increase of dry density,and the strength of soil can be increased by adding basalt fibre.With the increase of the mixing rate,the soil strength increases first and then decreases,and the optimal mixing rate is 0.3%,which makes the compressive strength and shear strength of basalt modified red clay the largest.Finally,the relationships between shear strength and compressive strength,dry density and fibre blending rate are established,respectively.(2)Through the standard consolidation test,shrinkage test and fracture test to compare basalt fibre modified red clay with plain red clay,the effect of basalt fibre mixed with dry density on deformation characteristics of basalt fibre modified red clay was analyzed.The results suggest that fibre’s addition strengthens the compression of red clay,and the final pore ratio keeps decreasing with the fibre blending rate.The compressibility keeps decreasing with the increase of dry density.The higher the dry density,the stronger the shrinkage inhibition ability of compacted soil samples;after adding basalt fibre,the linear shrinkage and volume shrinkage decrease at first and then increase.The basalt fibre with a 0.3% incorporation ratio can inhibit the shrinkage of soil samples most.The shrinkage of the mud soil sample,that is,fracture test,soil’s ability to resist water loss shrinkage cracking increases with the increase of the mixing rate.The higher the fibre mixing rate is,the higher the final soil moisture content is,the lower the fracture rate is.Finally,the relationships between linear shrinkage,bulk shrinkage,compression coefficient and compression modulus,and dry density and fibre blending rate are established,respectively.(3)The macro mechanical properties mechanism was elaborated by comparing the microstructure of basalt fibre modified red clay and plain red clay.The results manifest that basalt fibre can reduce pore and increase friction force between soil particles by contacting soil particles,effectively limiting soil particles’ movement,promoting the agglomeration of soil particles,and optimizing the strength and deformation performance of soil under stress.