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为了研究砂岩细观结构的冻融损伤特性,对砂岩共进行了180次冻融循环实验,利用核磁共振技术(NMR)对冻融循环后的岩样进行了检测和核磁共振成像分析,并采用分形理论计算了砂岩经历不同冻融循环后孔隙发育的分形维数。研究结果表明:随着冻融循环次数的增多,砂岩的质量、孔隙度、核磁共振弛豫时间T_2分布均会增大;核磁共振T_2谱分布表明,经历180次冻融后,砂岩的孔隙尺寸均会增大,尤其是中、小尺寸孔隙增大明显;在冻融作用下,砂岩的孔隙结构演化,在空间分布上具有分形特征,其分形维数出现逐渐增大的趋势。
In order to study the freeze-thaw damage characteristics of sandstone meso-structures, a total of 180 freeze-thaw cycles were performed on the sandstone. Rock samples after freeze-thaw cycles were analyzed by nuclear magnetic resonance (NMR) and analyzed by using magnetic resonance imaging Fractal theory was used to calculate the fractal dimension of sandstone under different freezing and thawing cycles. The results show that with the increase of the number of freeze-thaw cycles, the sandstone quality, porosity and NMR relaxation time T 2 distribution will increase. The T 2 NMR spectrum shows that after 180 freeze-thaw cycles, the pore size The pores of medium and small size increase obviously. Under the effect of freeze-thaw, the pore structure evolution of sandstone has fractal characteristics in spatial distribution, and its fractal dimension tends to increase gradually.