基于核磁共振的不同含水率黄土古土壤冻融循环试验研究  

FREEZE-THAW CYCLE EXPERIMENT OF LOESS PALEOSOL WITH DIFFERENT WATER CONTENT BASED ON NUCLEAR MAGNETIC RESONANCE

作　　者：叶万军[1] 强艳红 景宏君 邹愈 YE Wanjun;QIANG Yanhong;JING Hongjun;ZOU Yu(College of Architecture and Civil Engineering,Xi an University of Science and Technology,Xi an 710054,China;Shaanxi Science and Technology Holding Group Co.LTD.,Xi an 710077,China;Shaanxi Kekong Technology Industry Research Institute Co.LTD.,Xi an 710077,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]陕西科技控股集团有限责任公司,西安710077 [3]陕西科控技术产业研究院有限公司,西安710077

出　　处：《工程地质学报》2022年第1期144-153,共10页Journal of Engineering Geology

基　　金：陕西省重点研发计划项目(资助号:2017ZDXM-SF-082);国家自然科学基金(资助号:42072319)。

摘　　要：为明确不同含水率古土壤在冻融循环作用下其微观结构特性及古土壤损伤机制,采用核磁共振扫描仪对不同含水率冻融循环后的古土壤试样进行测试,研究冻融循环和含水率共同作用对古土壤微观结构的影响及土体内部损伤变化。结果表明:冻融循环下不同含水率使土体内部产生不同程度的损伤,损伤程度为含水率大的土体大于含水率小的土体。随着冻融循环次数增加,T;谱曲线信号幅度增加,孔隙结构改变,大孔隙、最大孔隙含量增加,中孔隙含量减小;同时含水率较大的土体孔隙体积增大幅度大于含水率较小的土体,说明在季节冻土区建设工程中含水率越大土体越易发生破坏,因此在工程中应注意防排水问题。依据损伤力学原理,得出土体颗粒连续性与孔隙率关系,进而得出有效应力与孔隙率关系;根据核磁扫描结果,建立孔隙率与冻融循环次数关系,最终推导出古土壤有效应力与冻融循环次数关系表达式。研究成果为季节冻土区古土壤地层建设工程提供理论指导。This paper aims to clarify the microstructure characteristics and damage mechanism of paleosol with different water contents under freeze-thaw cycles. It uses the nuclear magnetic resonance scanner to test the paleosol samples with different water contents after freeze-thaw cycles. It studies the combination of freeze-thaw cycles and water content on the microstructure of the paleosol and the internal damage changes of the soil. The results show that the different water contents under freeze-thaw cycles cause different degrees of damage to the interior of the soil. The damage degree is that the soil with high water content is greater than that with low water content. As the number of freeze-thaw cycles increases, the signal amplitude of the T;spectrum curve increases, the pore structure changes, the content of macropores and maximum pores increase, and the content of mesopores decreases. At the same time, the increase in pore volume of soils with larger water content is greater than that of soil with lower water content. These results show that the greater the water content in construction projects in seasonal frozen soil areas, the more likely the soil mass is to be destroyed. So the waterproof and drainage problems should be paid attention in the project. According to the principle of damage mechanics, the relationship between soil particle continuity and porosity is obtained. Then the relationship between effective stress and porosity is obtained. According to the results of nuclear magnetic resonance scanning, this paper establishes the relationship between porosity and the number of freeze-thaw cycles, and finally derives the expression of the relationship between the effective stress of the paleosol and the number of freeze-thaw cycles. The research results provide theoretical guidance for the construction projects of paleosol strata in seasonally frozen soil regions.

关 键 词：冻融循环 含水率 古土壤 核磁共振 损伤力学 

分 类 号：P642.3[天文地球—工程地质学]