Experimental Analysis On Microcosmic Study Of Weak Expansive Soil Improved By Silty Sand In The Yellow River Flood Area

In this article,the expansive soil in section IV of Lu Wang Grave section of Xinxiang,Henan Province is selected in Central Line Project of South-to-North Water Diversion.The Yellow River flood areasilty sandin Yuanyang County of Xinxiang is used as admixture to improve it.The expansive soil is formed by the dual erosion of the expansive rock by wind and water,and the properties and internal components of the expansive soil formed in different environments and regions are often anisotropic,while the composition,internal structure and microscopic structure determine the engineering characteristics of the soil.Soil composition determines its physical and mechanical properties,the content of montmorillonite in expansive soil affects the potential of swelling and shrinkage,the arrangement of internal particles of soil structure and pore structure features has a great influence on the strength and deformation capacity,therefore,to make a comprehensive analysis of expansive soil,we must begin from the material composition,and combined with the physical and mechanical experiments,and study the properties of the internal structure of soil from the microscopicpoint view.So in this acticle,on the basis of analyzing physical and mechanical properties in the geotechnical test,this acticle selects soil samples under different test conditions for microscopic test analysis: the test selects load-free inflation rate test,consolidation test,triaxial shear test,and the microstructure of soil under different test conditions for qualitative analysis,on the fractal characteristics of soil porosity change to do quantitative analysis.The research results of this paper show that:(1)Through the load-free inflation rate test and microscopic image after 0h,3h,24 h,72h immersion,and combined with X ray diffraction experiment for expansive soil physical composition,the size of expansive soil increased and potential mainly affected by the contact between the particles,arrangement,pore distribution and material composition of the content of montmorillonite.(2)Through consolidation test,triaxial shear test and corresponding microstructure analysis,it was found that the compressibility and strength characteristics of soil were mainly related to the arrangement of the structure between particles,the density of particles and the distribution characteristics of pores.(3)Through the quantitative analysis of microscopic images by IPP and MATLAB software,it was found that the expansive soil and the improved expansive soil had obvious fractal characteristics in pore distribution.And according to the fractal dimension of pores under different conditions obtained by calculation and analysis,it was found that with the increase of immersion time,the internal pore dimension of soil was increasing;the fractal dimension increased with the increase of consolidation pressure in consolidation test,and it appeared obvious turning at 400 k Pa;and the fractal dimension of soil pore increased gradually with the increase of confining pressure value.It was found that the fractal dimension had obvious regularity with the increase of immersion time,consolidation pressure and triaxial shear confining pressure.(4)Through the comparison and analysis of the microcosmic results under different experimental conditions,it was found that the overall fractal dimension of the improved soil was small,the internal particle structure was stable,the pore distribution was uniform,the structural integrity was good,and the improvement of expansive soil in the Yellow River flood area silty sand had a certain obvious effect.