泾阳浅层黄土细微观孔隙结构试验  

Meso and micro pore structure test of Jingyang shallow loess

作　　者：冯笑瑞 朱兴华[1,2] 孙恒飞 俱量 温瑞祥 肖永玖 FENG Xiaorui;ZHU Xinghua;SUN Hengfei;JU Liang;WEN Ruixiang;XIAO Yongjiu(School of Geological Engineering and Surveying,Chang’an University,Xi’an,Shaanxi 710054,China;Key Laboratory of Western Mineral Resources and Geological Engineering,Ministry of Education,Xi’an,Shaanxi 710054,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710054 [2]西部矿产资源与地质工程教育部重点实验室,陕西西安710054

出　　处：《水文地质工程地质》2024年第6期138-148,共11页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金基项目(442090053,42041006,41877249)。

摘　　要：降雨与灌溉是黄土地区最常见的地灾驱动力。通常情况下,入渗深度较浅且主要受细微观通道的控制,孔隙结构对渗流特性的影响十分显著。为了研究浅层黄土孔隙结构分布规律,以泾阳南塬黄土为研究对象,采用CT断层扫描法和压汞法分析黄土结构,观察并讨论细微观孔隙结构特性随黄土埋深的变化规律。研究表明:①泾阳浅层黄土根据其孔隙结构特征可划分为三层,1~2 m为第一层,3~4 m为第二层,5 m为第三层;②孔径小于1.0 mm的孔隙占总孔隙数量的95%以上,以类球状和柱状的封闭孔隙为主;③孔径大于0.8 mm的孔隙占总孔隙体积的65%以上,多为枝杈状和柱状的连通孔隙;④随着埋深的增加,连通性逐渐降低,大孔隙的变形破坏对黄土结构的稳定起着关键作用;⑤根据压汞试验可知,集粒内孔隙以0.2μm为界,随着埋深的增加左侧孔隙占比无明显变化,右侧随之增大。研究成果可为进一步探索浅表层黄土细微观孔隙渗流机制提供参考。Rainfall and irrigation are the most common driving forces of geological disasters in loess areas.Generally,the infiltration depth is shallow and mainly controlled by microchannels.The pore structure has a significant influence on the seepage characteristics.Aiming to study the distribution of pore structure in shallow loess,this study analyzes the structural samples of loess using CT tomography and mercury intrusion methods in the southern plateau of Jingyang,Shaanxi Province.The changes in meso and micro pore structure characteristics with the burial depth of loess are observed and revealed.The results show that Jingyang shallow loess can be divided into three layers according to its pore structure characteristics:①1−2 m as the first layer,3−4 m as the second layer,and 5 m as the third layer;②The diameter of more than 95%of the total pores are less than 1.0 mm,which mainly are spherical and columnar closed pores;③while more than 65%of the total pore are larger than 0.8 mm,and most of them are branched and columnar connected pores;④With depth increasing,the pore connectivity gradually decreases,and the deformation and failure of macropores play a key role in the stability of loess structure;⑤In the mercury intrusion test,intragranular pores are bounded by 0.2μm.The proportion of pores on the left side shows insignificant change with depth,while on the right side,it increases with depth.This study provides a basis for further exploring the micro pore seepage mechanism of shallow loess in the future.

关 键 词：孔隙大小 孔隙形状 CT试验 马兰黄土 孔隙分类 

分 类 号：P642.2[天文地球—工程地质学]