Experimental Study On Soil Water Characteristics Under The Action Of Water Repellent Agent

In the field of civil engineering,most of the soil in the nature is hydrophilic.With the large-scale development of modern human activities and engineering construction,engineering problems caused by the hydrophilicity of soil become more and more prominent.Slippery and landslide shear strength decrease,permeability damage phenomenon of piping and soil flow,ground deformation,seawater intrusion and other engineering problems,are due to the soil has good hydrophilicity.The serious damage to the building is often characterized by long-term potential danger.Therefore,the soil particles can be modified by adding water repellent to make it change from strong hydrophilicity to weak hydrophilic or even water repellency.Water can not easily infiltrate into the inner pores of the soil,and the seepage is not easy to occur,and the engineering problems caused by seepage are not easy to appear.In addition,the internal water repellent soil pore water cannot easily overflow outside,the water retention of soil is greatly improved,the need for preserving soil rich water engineering benefit.Moreover,the water repellent soil can be reused by some engineering waste materials by technical means,which can turn waste into treasure,reduce environmental pollution and accumulate land occupation,and become a resource of reclaimed soil.The study of water repellent soil soil not only increases the interdisciplinary and application of the subject,but also provides a new way of thinking for the solution of engineering problems.In this paper,the effect of soil modification and water repellency,the permeability and shear strength of soil are systematically studied by using the experimental method.There are mainly:（1）Evaluation of modified effect of water repellent soil.The water repellent effect of dichlorodimethylsilane modified sand is the best,and its water repellency is stable for a long time,and the soil particles are dispersed and non agglomeration.Silane coupling agent modified sand has good water repellency,but the soil particles are easily solidified into blocks,and it is difficult to prepare the samples.The water repellency of sodium dodecyl sulfate（SDS）modified sand is not obvious,and it is easy to lose.NoKe Octadecyl amine modified clay has good repellency.When the mass ratio of the alkyl amine to clay is 0.2%,it has reached a serious level of water repellency,and its water repellency can also remain stable for a long time.When the modified clay is added to ordinary sand,the degree of water repellency is obviously changed under different clay parameters.When the mass ratio of clay to sand is 4%,the degree of water repellency can reach serious water repellency level.（2）Water repellent evaluation standard.The infiltration time of two kinds of glutaraldehyde solution with different volume fraction can be used as an indicator to test the water repellent grade of water repellent soil.（3）Test of permeability of modified soil.The permeability of the modified soil decreases with the increase of the content of the repulsion agent.K = 11.73e^-0.932 x can be used to describe the relationship between the content of the repellant and the permeability coefficient.（4）Shear strength test of modified soil.With the increase of water repellent content,the shear strength of modified soil decreases.The relationship between the content of the repulsion agent and the internal friction angle can be described by φ=-2.13x+36.08.This indicates that there is a negative correlation between the shear strength of the modified soil and the water water cut rate,that is,the higher the water content,the smaller the shear strength.The research results in this paper can provide experimental basis for the application of water repellent soil to the field of soil water engineering,and will further promote the cross interaction and development of soil science and civil engineering.