黄土显微结构特征与震陷性

黄土的动力学性质与其微观结构有着密切的关系,而黄土显微结构特征因生成地质环境和应力历史的不同有较大差别,其中,架空孔隙的大小,颗粒粒径分布,颗粒类别均是黄土产生残余应变的主要内因,它们直接影响到黄土结构的力学稳定性。本文基于西安、宝鸡、山西、兰州、通渭、永登、会宁等地黄土的电镜照片,用图像处理软件获取相关参数,并将其与震陷系数进行对比分析研究,结果发现,架空孔隙面积,粒径偏斜度和粒径分布峰值与黄土震陷系数具有较好的相关性。为此,作者将架空孔隙面积与粒径偏斜度之和定义为表征黄土震陷性大小的“微结构特征参数”。进而结合对不同地区黄土孔隙排列方式、颗粒特点及其胶结程度等的分析,按照震陷性强弱提出了较为简单的黄土微结构分类方法。

Microstructure characteristics and seismic subsidence of loess

It was found that the dynamic characteristics of loess were closely related to the microstructure.Loess formed under different circumstances conditions and stress histories has different microstructure characteristics.In many factors,the size of trellis pores,distribution in particles size and kinds of particles are key internal factors for residual strain development of loess,which also influence the stability of loess’ microstructure.Based on the microstructure images of loess samples secured from main loess regions in China such as Xi-an,Bao-Ji,,Shan-Xi,Lan-Zhou,,Tong-Wei,Yong-Deng,Hui-Ning,done by electron microscope scanning,the relevant data were obtained by the imagination processing software.The comparative analysis between seismic subsidence coefficient and those parameters show that the area of trellis pores.The declination of particle distribution and peak value of particle size distribution are well correlated to the seismic subsidence coefficient of loess.The sum of the area of trellis pores and the declination of particle distribution are defined as characteristic parameters of microstructure related to seismic subsidence of loess by authors.Then,a simple but reasonable microstructure classification of seismic subsidence is proposed in terms of microstructure,particles and pores as well as their distribution patterns and cementation.