Experimental Study On Strength And Deformation Of Basalt Fiber Modified Soil

After many years of rapid development,fiber reinforcement technology has become a fine soil modification technology.The strength of the soil after reinforcement is generally improved significantly,and the deformation characteristics will change greatly.At present,there are many materials used in soil modification,such as lime.cement and so on,however,most traditional materials have disadvantages such as low elastic modulus,poor reinforcement effect and large pollution.As a result,new materials such as basalt fiber,geogrid,polypropylene and nanoscale bentonite appeared Compared with other materials,basalt fiber has the advantages of high strength,good mechanical properties,good dispersion,less pollution,aging,acid resistance,low cost and so on.At present,it has good application in concrete reinforcement,building repair and road construction,but the research on soil reinforcement and soil improvement is relatively less.Bentonite is a widely used modified material,consisting of fine clay minerals,which has excellent adsorbability,impermeability and adhesion.At present,it has a good practical application in the field of asphalt and concrete modification and the field of water conservancy project,but the application of soil improvement is relatively small.Therefore,in view of the fact that basalt fiber and bentonite are less studied in soil modification at present,a series of indoor geotechnical tests have been carried out.It mainly includes one-dimensional consolidation test,direct shear test and direct shear creep test.The effects of basalt fiber on the physical properties and mechanical properties of soil consolidation,compression,permeability,creep and shear properties were investigated.The main conclusions are as follows:1.Through indoor one-dimensional consolidation test,it is found that the incorporation of fiber contributes to the consolidation of clay and enables the clay to achieve higher degree of consolidation in the same time.From the e-t and e-p curves of clay,it is found that the increase of fiber content makes the pore ratio of clay decrease.When the fiber content is 0.4%,the fiber has the most significant effect on improving the coefficient of consolidation of the clay.Excessive fiber will make the clay coefficient smaller in the same time.Adding more fibers into clay can make the clay have greater secondary consolidation coefficient in the same time.2.Under low pressure,the incorporation of fiber can significantly increase the compression properties of clay.When the consolidation pressure is higher than 400kPa,the compression coefficient of clay under different fiber content is basically the same.The change of permeability coefficient of clay is similar to that of compression coefficient.3.Through the direct shear creep test,it is found that the addition of fiber can not only reduce the creep of clay,but also improve the shear strength and long term strength of clay.But the fiber can't change the inherent creep mode of clay itself.Fiber has the best dosage for the reduction of clay creep,shear strength and long-term strength.The effect of fiber content increased by 0.4%is the most obvious.4.Through the direct shear test,it is found that the incorporation of fiber has great effect on improving cohesive force of clay,and the effect of fiber on internal friction angle is small.Fiber can reduce the shearing phenomenon during shearing.When the fiber content is 0.4%,the fiber has the best effect in reducing the shearing phenomenon.5.When the content of water is 0%,the fiber content is 0.8%and the content of bentonite is 10%,the shear strength of sand reaches the maximum.The shear strength of sand increases with the increase of bentonite and fiber production.Bentonite,water and fiber have great influence on the shear dilatancy and shrinkage characteristics of sand.The soil samples mixed with bentonite and water are mainly dilatant,and the soil samples doped with fiber are mainly shear shrinkage6.The influence of water content on cohesive force of sand is smaller than that of bentonite and fiber;The influence of water content on the internal friction angle of sand is larger than that of fiber and bentonite.