压实黄土在固结和剪切过程中的微结构演化

Microstructural evolution of compacted loess during consolidation and shearing

为了解压实黄土在固结和剪切过程中微结构的演化过程,运用三轴试验和MIP技术,得出不同应力应变状态的压实黄土试样的孔径分布曲线,通过分析压实土样的孔径分布特征,研究压实黄土在固结和剪切过程中的微结构演化规律。结果显示,该压实黄土在剪应力作用下表现为强烈的剪缩特性,固结和剪切阶段的孔径分布演化规律相似,粒内孔隙没有受到影响,只有粒间孔隙被压缩。另外,基于孔径分布曲线,利用分形理论计算得出的试样孔隙体积分形维数变化不大,表明在固结和剪切过程中,孔隙表面的粗糙程度变化不大,且试样的分形维数和孔隙比、轴向应变之间无明显相关关系。研究结果说明了压实黄土的力学响应是集粒间相互作用的结果,而非颗粒与颗粒之间相互作用的结果。

To understand the microstructural evolution of compacted loess during consolidation and shearing,the triaxial tests and the MIP technology are used to acquire the pore-size distribution curve of compacted loess specimens with different stress and strain states.By analyzing the pore-size distribution characteristics of compacted loess specimens,the microstructural evolution of compacted loess during consolidation and shearing is studied.The results show that the compacted loess tested is strongly contractive during shearing,and the evolution of the pore-size distribution of compacted loess during consolidation is similar to that during shearing.The intra-aggregate pores are not affected,only the inter-aggregate pores are compressed.In addition,based on the pore-size distribution curve,the fractal dimension of each specimen is calculated by the fractal theory,which changes a little from specimen to specimen.It is indicated that the roughness of pore surface changes little during the process of consolidation and shearing,and there is no obvious correlation between fractal dimension,void ratio and axial strain.The research results indicate that the mechanical response of compacted loess is due to the interaction between aggregates,while not between particles.