Evolution of Pore Structure and Multifractal Characteristics of Freeze-Thaw Red Sandstone
In order to explore the pore structure damage characteristics of the sandstone in the cold region under the freeze-thaw cy-cle,the nuclear magnetic resonance(NMR)test was carried out on the red sandstone samples undergoing different freeze-thaw cycles.Combining the multifractal theory,the evolution law of the pore structure in red sandstone at different scales under freeze-thaw cycles was explored.The results show that the freezing and thawing promotes the development of pore structure of red sandstone.The T2 spec-trum of red sandstone without freeze and thaw shows 3 peaks,and 4 peaks appeared in the T2 spectrum of freeze-thaw red sandstone.It reflects the complex pore structure evolution of red sandstone during freezing and thawing.Mono-fractal does not characterize the pore structure of red sandstone micro-pores.However,both the micro-pores and medium macro-pores of red sandstone have good multifractal characteristics.Multifractal parameters are highly linearly associated with porosity.In the micro-pores,mono-fractal dimension D2 is negatively correlated with the porosity,the overall heterogeneity parameters D(0)-D(1)and low probability parameters D(-10)-D(0)negatively correlated with porosity,the Hurst index H is positively correlated with porosity.In the macro-pores,D(0)-D(1),D(-10)-D(0)and H are positively correlated with porosity.The evolution of freeze-thaw red sandstone is analyzed by multi-fractal,it provides a basis for further study of the damage mechanism of freezing-thawing red sandstone.
万方数据
维普
