土体微观结构对冻胀影响的灰色关联及粗糙集评价

Estimate Between Soil Microstructure and Its Frost Heave Using Grey Relation Analysis Method and Rough Set Theory

以季冻区粉土为研究对象,进行不同条件下室内冻胀试验,测得冻胀指标——冻胀率;同时运用扫描电子显微镜WD-5图像处理系统提取并定量化冻胀前土样微观结构参数(包括孔隙参数和结构单元体参数)。由于结构对冻胀影响具有非线性、复杂性、模糊性等特点,选择灰色关联法及粗糙集2种非线性评价方法,评价各结构参数对冻胀率的影响程度。评价结果表明:与冻胀率关联度较高的孔隙参数为形态分布分维数、平均丰度、平均圆形度和平均各向异性率,单元体参数为平均各向异性率、形态分布分维数和定向概率熵。粗糙集约简结果中,对冻胀影响较明显的孔隙参数为平均各向异性率、平均丰度、定向分维数和形态分布分维数,单元体参数为形态分布分维、平均各向异性率、平均形状系数。比较2种评价方法所得结果,分析其中的异同。最后综合考虑2种评价结果,确定8个对冻胀意义较明显的结构参数:孔隙的形态分布分维、平均丰度、平均各向异性率、定向分维数;单元体的平均各向异性率、形态分布分维、平均形状系数和定向概率熵。

Silty soils as research objects come from seasonal frost zone in Northeast China.First,experiments of frost heave under different conditions are tested in laboratory to get index of each sample which can show the degree of frost heave,namely,the ratio of frost heave.Microstructure parameters of each sample are selected and quantitative analysed by WD-5 SEM before tests.As the relationship between microstructure parameters and ratio of frost heave are nonlinear,complex,indiscernibility,a grey relation analysis and rough set theory are selected to evaluate influences of each parameter on frost heave.Results from grey relation analysis get some parameters of pore and unit which have far-reaching impact on frost heave.They are of pore parameter,that is shape distribution fractal dimension,mean abundance ratio,mean circularity,mean anisotropy.And the unit parameter are mean anisotropy,shape distribution fractal dimension,and description probability entropy.The results from the method of rough set also get some parameters of pore and unit which have far-reaching impact on frost heave.The opore parameters are mean anisotropy,mean abundance ratio,direction fractal dimension,shape distribution fractal dimension,and unit parameters are shape distribution fractal dimension,mean anisotropy,mean shape coefficient,respectively.Comparing and analyzing these results from different method,two results are considered synthetically,eight parameters influence frost heave obviously,they are four pore parameters of shape distribution fractal dimension,mean abundance ratio,mean anisotropy,direction fractal dimension and four unit parameters of mean anisotropy,shape distribution fractional dimension,mean shape coefficient,description probability entropy.