冻融-干湿循环下硫酸盐渍土强度劣化的宏微观响应  

Macro-and-microscopic Responses of Strength Deterioration ofSulphate Saline Soils under Freeze-Thaw and Dry-Wet Cycles

作　　者：雷过 张卫兵[1,2] 李晓 刘臻祥 周鑫磊 LEI Guo;ZHANG Wei-bing;LI Xiao;LIU Zhen-xiang;ZHOU Xin-lei(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Engineering Research Center of Ministry of Education for Efficient Utilization of Modern Agricultural Water Resources in Arid Regions,Yinchuan 750021,China)

机构地区：[1]宁夏大学土木与水利工程学院,银川750021 [2]旱区现代农业水资源高效利用教育部工程研究中心,银川750021

出　　处：《长江科学院院报》2023年第6期154-159,165,共7页Journal of Changjiang River Scientific Research Institute

基　　金：宁夏自然科学基金项目(2021AAC03067);宁夏大学研究生创新项目(GIP2021051);宁夏高等学校一流学科建设(国内一流建设学科)项目(NXYLXK2021A03)。

摘　　要：冻融-干湿循环是引起硫酸盐渍土强度劣化的主要原因,而土体微观孔隙结构与强度之间有紧密的联系。通过无侧限抗压强度试验、压汞试验、电镜扫描(SEM)试验,采用全局优化法(UGO)分析数据,ImageJ2X处理SEM图像,探究了冻融-干湿循环下硫酸盐渍土强度劣化的宏微观响应关系。结果表明:①冻融-干湿循环作用下,无侧限抗压强度随含盐量呈现先增大后减小的变化趋势,当压实度较低时强度峰值对应的含盐量低;从孔隙分布得出,1~10μm的孔隙占比为强度劣化的阈值,当其占比>50%时强度出现劣化,且劣化现象不可逆。②冻融-干湿作用下的无侧限抗压强度值与微观参数的歪度、结构优度间存在相关性,无侧限抗压强度与歪度呈现正相关,与结构优度呈负相关,且结构优度比歪度对强度影响更加显著。③影响无侧限抗压强度宏观指标劣化程度的微观参数依次为结构优度、歪度、分选系数、平均孔喉半径。本研究从定量分析的层面探究了硫酸盐渍土的宏微观响应关系,为进一步研究盐渍土工程性质提供参考。Under freeze-thaw-dry-wet cycles,the main cause of strength deterioration in sulphate saline soils is the microscopic pore structure of the soil.In this study,we investigated the macro and micro response relationships of strength deterioration using unconfined compressive strength tests,mercury compression tests,electron microscopy scanning tests,universal global optimization(UGO)analysis of data,and ImageJ2X processing of SEM images.The results demonstrate that:(1)The unconfined compressive strength tends to increase and then decrease with the salt content under freeze-thaw-dry-wet cycles,and the peak strength corresponds to a low salt content when the compaction is low.Additionally,the percentage of pores between 1-10μm is the threshold for strength deterioration,which is irreversible,occurs when the percentage is higher than 50%.(2)Under freeze-thaw-dry-wet cycles,the unconfined compressive strength is correlated with the skewness and structural merit of the microscopic parameters.Unconfined compressive strength shows a positive correlation with skewness and a negative correlation with structural merit,with structural merit having a more significant effect on strength than skewness does.(3)Structural merit,skewness,sorting factor,and mean pore throat radius,in descending order,are the microscopic parameters that affect the deterioration degree of macroscopic indicators of unconfined compressive strength.This study provides a reference for further research on the engineering properties of saline soils by exploring the macro-and-micro-response relationships of sulphate saline soils at the quantitative level.

关 键 词：强度劣化 宏微观响应 硫酸盐渍土 冻融-干湿循环 无侧限抗压强度试验 压汞试验 电镜扫描试验 全局优化法 

分 类 号：TU448[建筑科学—岩土工程]