Microstructure Damage Characteristics of Soft Soil Subjected to Triaxial Loading
Stress-controlled triaxial undrained shearing tests and field emission electron microscopy scanning tests were carried out for natural soft soil in order to study the macroscopic and microscopic evolution characteristics during the whole process subjected to the triaxial loading,and to reveal the mi-croscopic structure evolution mechanism of natural soft soil.The results show that microscopic struc-ture continually undergoes damage during the stress process,with an increase in the number of large-sized and medium-sized pores and a looser distribution of pores and soil particles.Therefore,the micro damage of soft soil is a comprehensive reflection of the changes in soil particles and pores distribution.The distribution fractal dimensions of pores and soil particles are nonlinear to shear stress ratio with an obvious turning point.After the point,their distribution fractal dimensions increase significantly.The numbers of large-sized and medium-sized pores near the shear band are much larger than that outside the band,and the distribution fractal dimensions of pore and soil particles is large.However,the distribu-tion fractal dimensions at different positions become close to a critical value at soil failure.When the shear stress ratio is 1.22,the critical values were about 1.70 for pores,1.92 for soil particles.