Experimental Study On Biochar To Improve The Physical And Mechanical Properties Of Spoil

As a new type of green material,biochar is widely used in agricultural production.It has many advantages such as reducing pollution and increasing crop yield.However,its improvement effect on engineering soils is not yet known.In this paper,three types of typical spoils(ordinary yellow clay,red clay,expansive soil)were selected from the spoil ground generated in the Guangxi project,and they were mixed with different amounts(0%,2%,5%,8%)The biochar blended with the soil,the permeability,shear strength and compressibility of the mixed soil were measured through experiments,and the abandoned soil slope model was established using Midas software to calculate the stress,strain and stability of the soil slope with the addition of biochar Sexual changes.The main conclusions are as follows:(1)The cumulative infiltration volume and permeability coefficient of the mixed soil are measured by the variable water head method.It is found that when the biochar content is less than 2%,the permeability of red clay does not change much;when the biochar content is less than 5%,ordinary The permeability of yellow clay and expansive soil does not change much,because biochar has a certain hydrophobicity,and the particles change the pore structure.When the content reaches 8%,the permeability coefficients of the three types of soil are significantly increased,which is beneficial to the drainage of the soil.(2)Direct shear test results found that when the biochar content is less than 5%,the cohesive force of ordinary yellow clay and red clay changes little;while for expansive soil,even if the content reaches 8%,its cohesion The force still changes very little.In addition,when the amount of biochar is less than 5%,the friction angle in the three types of mixed soils has increased to varying degrees,but when the amount reaches 8%,the friction angle in the three types of mixed soils begins to decrease,which is because the biochar Change the soil particle gradation.(3)The results of the lateral compression test found that when the biochar content is less than 2%,the compressibility of red clay and expansive soil does not change significantly.After exceeding this value,the compressibility will increase significantly,when the biochar content is greater than 5 %,ordinary yellow clay also showed similar characteristics.The reason is that the biochar's own hardness and small particles block the pores of the soil,and when it exceeds,it is related to the increase of the pores of the particles.(4)In order to comprehensively evaluate the impact of biochar on the strength and stability of three types of soil,a soil model was established using Midas GTS software,and the values were assigned according to the experimental measured parameters.Simulations show that: in terms of strain,ordinary yellow clay is the smallest,red clay is the second,and expansive soil is the largest.In addition,when the amount of biochar in ordinary yellow clay and expansive soil is 2% and 5%,the strength and stability of the soil are improved.Therefore,different amounts of biochar can be used to improve different types of soil.This result has certain guiding value for the slope stability management of the spoil ground.