青海地区泥岩膨胀特性与微观结构

Swelling Characteristics and Microstructure of Mudstone in Qinghai Area

为研究不同单元体泥岩膨胀特性与微观结构的关联性。对青海省东北部的泥岩进行调查研究,选用扫描电镜(scanning electron microscope,SEM)对泥岩进行观测,利用图形软件分析岩石内部的结构。通过自由膨胀试验、侧向约束膨胀试验、膨胀力试验来探究不同单元体泥岩的宏观膨胀。通过获取的数据针对泥岩孔隙分形特征展开分析,运用灰色关联法建立宏观膨胀与微观结构之间关系。研究结果表明:①N型泥岩试样孔隙多,膨胀潜势不强,M型泥岩试样结构紧密,孔隙较少,矿物成分较多,膨胀潜势相对较强;②不同单元体泥岩试样的分形维数与膨胀率(力)呈负相关,且M型泥岩试样的分形维数在膨胀率(力)的拟合度要高于N型泥岩试样;③不同单元体的膨胀率(力)与平均孔径、圆度、分形维数、面孔率均有关联,尤其是孔隙的圆度和分形维数关联性最大。研究成果为宏-微观之间泥岩关联性的认识提供参考,对该地区膨胀岩(土)工程建设具有借鉴意义。

In order to study the correlation between swelling characteristics and microstructure of mudstone of different units.The mudstone in the northeast of Qinghai Province was investigated,and the scanning electron microscope(SEM)was used to observe the mudstone,and the graphic analysis software was used to analyze the internal structure of the rock.Through the free expansion test,lateral restraint expansion test and expansion force test,the macroscopic expansion of mudstone with different unit bodies was investigated.Based on the obtained data,the fractal characteristics of mudstone pores were analyzed,and the relationship between macroscopic expansion and microstructure was established by using the grey correlation method.The results show these as follows.The N-type mudstone has more pores,and the swelling potential is not strong,while the M-type mudstone has a tight structure,less pores,and more mineral components,and the swelling potential is relatively strong.The fractal dimension of mudstone samples with different units is negatively correlated with the swelling rate(force),and the fitting degree of the fractal dimension of M-type mudstone samples in the swelling rate(force)is higher than that of N-type mudstone samples.The expansion rate(force)of different elements is correlated with the average pore size,roundness,fractal dimension and face rate,especially the roundness and fractal dimension of pores are most correlated.The research results provide a reference for understanding the relationship between macro and micro mudstone,and have reference significance for the construction of expansive rock(soil)engineering in this area.