Study on Micro-pore Structure and Fractal Characteristics of Modified Soft Clay Under Freezing-thawing Cycle
In order to study the influence of freeze-thaw action on the pore structure and fractal characteristics of soft clay,taking the soft clay in a certain area of Jilin Province as an example,Nuclear Magnetic Resonance(NMR)technology was used to test the soft clay under different freeze-thaw cycles,compaction coefficients and lignin fiber content.The Pore Size Distribution(PSD)of soft soil samples was obtained by T2 NMR spectrum,and fractal theory was introduced to describe the fractal characteristics of PSD.The results show that with the increase of freeze-thaw cycles,the proportion of small pores decreases,and the proportion of medium and large pores increases significantly.The role of freeze-thaw cycles makes the pores of soil samples continuously transform to larger pores.The fractal dimension of bound fluid pore of soil sample Dmin is between 0.167 and 0.445,and the fractal dimension of movable fluid pore of soil sample Dmax is between 2.832 and 2.957.The fractal characteristics of movable fluid pores are more obvious than those of bound fluid pores,which indicates that freezing and thawing mainly affect the macropores of soil samples.The fractal dimension increases with the increase of freeze-thaw cycles,and the growth rate gradually decreases,and finally tends to be stable.The fractal dimension Dmin of bound fluid pores has no obvious linear relationship with the compaction coefficient,while the fractal dimension Dmax of movable fluid pores has a negative correlation with the compaction coefficient.
freeze-thaw cyclesoft clayfractal dimensionNuclear Magnetic Resonance(NMR)pore structure