灌溉条件下黑方台黄土湿陷特征及其内在机理  

Collapsibility of the loess soils on Heifangtai tableland due to wetting by flooding irrigation and its mechanism

作　　者：文宝萍[1] 余志山 黎志恒 冯传煌 徐秀娟[1] 闫亚景[1] 

机构地区：[1]中国地质大学(北京)水资源与环境学院,北京100083 [2]甘肃省地质环境监测院,兰州730050

出　　处：《兰州大学学报（自然科学版）》2015年第6期777-785,共9页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金项目(40872182)

摘　　要：基于室内试验，系统分析了不同初始含水量、增湿-减湿循环交替、渗透溶滤等多个条件下黑方台黄土的湿陷特性．基于微观结构定性和定量分析，探讨了黑方台黄土湿陷的内在机理．研究发现，黑方台黄土湿陷终止于饱和度52％-65％的非饱和状态；增湿-减湿循环交替4次后，黄土湿陷变形微弱；易溶盐淋滤时黄土湿陷变形持续．湿陷变形后的微观结构变化揭示出黑方台黄土湿陷的本质是黄土内架空大孔隙和支架小孔隙塌落．毛细管作用、孔隙压密作用、盐分溶解作用均对黑方台黄土湿陷有所贡献．但是盐分溶解作用的贡献远小于前二者，并且盐分溶解作用以易溶盐溶解为主．毛细管作用和孔隙压密作用的贡献大小取决于黄土中孔隙的分布和湿陷变形的发展阶段．An experimental study was made on the collapsibility of the loess soils in Heifangtai tableland due to wetting by flooding irrigation and also its mechanism. It was found that the collapses of loess soils in Heifangtaifinishes occurred under an unsaturated state of 52% to 65% saturation for the irrigated loess soils and, for those not yet irrigated, very weak collapses occurred when very wet and slightly wet circles were up to 4; there was some collapse when soluble salts within the loess was leaked. The microstructure under SEM and porosity measurement using the mercury injection apparatus revealed that collapses of loess soils after irrigation were attributed to the collapse of macro-size pores and some micor-size pores within the soils. It was further analyzed that suction, compaction and dissolution of soluble salts within the soils contributed to their collapses, of which, contributions of suction and compaction seemed to be much greater than that of dissolution of soluble salts.

关 键 词：大水漫灌 湿陷 增湿-减湿循环 孔隙塌落 黑方台黄土 

分 类 号：P642.22[天文地球—工程地质学]