黄土粒度组成对其渗透系数各向异性影响的试验研究  

Experimental study on influence of particle size composition on permeability coefficient anisotropy of loess

作　　者：赵茜 苏立君[2,3,4] 刘华 何江涛[1] 杨金熹 ZHAO Qian;SU Lijun;LIU Hua;HE Jiangtao;YANG Jinxi(School of Civil Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;Center for Excellence in Tibetan Plateau Earth Sciences,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]中国科学院·水利部成都山地灾害与环境研究所,四川成都610041 [3]中国科学院青藏高原地球科学卓越创新中心,北京100101 [4]中国科学院大学,北京100049

出　　处：《中南大学学报（自然科学版）》2020年第6期1615-1626,共12页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51278397,51608436);陕西省自然科学基础研究计划(2018JQ5003);陕西省教育厅自然科学专项研究计划(18JK0478)。

摘　　要：为了研究黄土粒度组成与其渗透系数各向异性之间的关系,从黏黄土、黄土和砂黄土区域纵向选择西安、延安和米脂三地黄土作为研究对象,通过颗粒分析和三轴渗透试验,并结合电镜扫描手段(SEM)得到宏-微观不同尺度下黄土的粒度组成差异和渗透系数各向异性的空间分布特征。基于试验数据的规律性,提出通过粒度分布预测黄土渗透系数的经验公式,并选择4处粒度差异显著的黄土渗透试验数据对该公式进行验证分析。研究结果表明:随地域由南向北延伸(西安-延安-米脂),黄土的细粒质量分数逐渐减少,粗粒质量分数逐渐增多,粒度分布曲线由"双峰"向"单峰"过渡。黄土中竖向尺度较大的缝隙状狭长孔隙与支架孔隙是能够发育成次生管状大孔隙的微观结构基础,不同评价尺度下的孔隙特征与三地黄土竖直向渗透系数大于水平向渗透系数时的试验结果相吻合,且黏粒质量分数越多,其渗透系数越小,纵横向渗透差异越明显。本文提出的黄土渗透系数预测公式具有普适性,可供工程实际参考。In order to investigate the relationship between loess particle size composition and permeability coefficient anisotropy,loess samples including clayey loess,loess and sandy loess were collected vertically from Xi'an,Yan'an and Mizhi,respectively.Particle size distribution tests,triaxial permeability tests and scanning electron microscopy(SEM)were conducted to obtain the spatial distribution of particle size composition and permeability coefficient anisotropy of loess at macroscopic and microscopic evaluation scales.Based on the test results,an empirical formula for predicting loess permeability coefficient by particle size distribution was proposed,which was then verified by four loess permeability test data with significant difference in particle size.The results show that as the geographical location varies from south to north,the fine particle mass fraction of loess decreases and the coarse particle mass fraction increases gradually.Particle size distribution curves change from"double peak"to"single peak".The narrow slit pores and the inter-particle voids with larger vertical dimension in the loess can be used as the microcosmic manifestation of secondary tubular macropores.The pore characteristics at different evaluation scales are consistent with the test results when the vertical permeability coefficient of loess is higher than that in the horizontal direction of Xi'an,Yan'an and Mizhi loess.Moreover,the higher the clay mass fraction of loess is,the smaller the permeability coefficient is and the more obvious the difference of vertical and horizontal permeability is.The proposed formula for predicting loess permeability coefficient is proved to be suitable for the reference of practical engineering.

关 键 词：黄土 粒度组成 渗透系数 各向异性 空间分异性 

分 类 号：TU444[建筑科学—岩土工程]