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,1~10 μm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。
Abstract
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 1-10 μm 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
Key words
degradation of strength /
macro-and-micro responses /
sulfate saline soil /
freeze-thaw and dry-wet cycles /
unconfined compressive strength test /
mercury compression test /
electron microscopy scanning test /
universal global optimization
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 王海涛, 张远芳, 成 峰, 等. 冻融循环作用下盐渍土抗剪强度变化规律研究[J]. 地下空间与工程学报, 2016, 12(5): 1271-1276.
[2] 马君泽, 张卫兵, 张 笑. 干湿循环作用下硫酸盐渍土强度特性试验研究[J]. 地下空间与工程学报, 2020, 16(3): 704-713.
[3] FENG R, WU L, WANG B. Numerical Simulation for Temperature Field and Salt Heave Influential Depth Estimation in Sulfate Saline Soil Highway Foundations[J]. International Journal of Geomechanics, 2020, 20(10): 4020196.1-4020196.12.
[4] 刘 凯, 张远芳, 张运海, 等. 冻融循环条件下亚氯盐渍土盐冻胀试验研究[J]. 长江科学院院报, 2018, 35(5): 93-96, 102.
[5] 应 赛, 周凤玺, 文 桃, 等. 硫酸盐渍土降温过程中的盐胀与冻胀特性[J]. 长江科学院院报, 2021, 38(6): 116-122.
[6] L Q, JIANG L, MA B, et al. A Study on the Effect of the Salt Content on the Solidification of Sulfate Saline Soil Solidified with an Alkali-Activated Geopolymer[J]. Construction and Building Materials, 2018, 176: 68-74.
[7] 宫经伟, 王 亮, 慈 军, 等. 硫酸盐含量对全固废材料固化盐渍土抗压强度的影响[J]. 长江科学院院报, 2021, 38(2): 73-79.
[8] YU Z, XU G, KANG X, et al. Unconfined Compressive Strength of Sulphate Saline Soil with Different Salt Content and Lime Proportion[J]. Electronic Journal of Geotechnical Engineering, 2016, 21(26): 10203-10214.
[9] 吕擎峰, 周 刚, 王生新, 等. 固化盐渍土核磁共振微观特征[J]. 岩土力学, 2019, 40(1): 245-249, 259.
[10]吕擎峰, 王子帅, 何俊峰, 等. 碱激发地聚物固化盐渍土微观结构研究[J]. 长江科学院院报, 2020, 37(1): 79-83.
[11]张 伟, 陈正汉, 黄雪峰, 等. 硫酸盐渍土的力学和细观特性试验研究[J]. 建筑科学, 2012, 28(1): 49-54.
[12]ZHANG W, MA J, TANG L. Experimental Study on Shear Strength Characteristics of Sulfate Saline Soil in Ningxia Region under Long-Term Freeze-Thaw Cycles[J]. Cold Regions Science and Technology, 2019, 160: 48-57.
[13]ZHANG J, LAI Y, LI J, et al. Study on the Influence of Hydro-Thermal-Salt-Mechanical Interaction in Saturated Frozen Sulfate Saline Soil Based on Crystallization Kinetics[J]. International Journal of Heat and Mass Transfer, 2020, 146: 118868.
[14]王春雷, 姜崇喜, 谢 强, 等. 析晶过程中盐渍土的微观结构变化[J]. 西南交通大学学报, 2007, 42(1): 66-69.
[15]色麦尔江·麦麦提玉苏普, 陶士超. 改良盐渍土强度变形及其微观特性试验研究[J]. 长江科学院院报, 2022, 39(6): 113-119, 132.
[16]杨 俊, 雷俊安, 张国栋. 冻融循环对风化砂改良膨胀土无侧限抗压强度影响研究[J]. 长江科学院院报, 2016, 33(1): 83-88.
[17]唐朝生, 施 斌, 王宝军. 基于SEM土体微观结构研究中的影响因素分析[J]. 岩土工程学报, 2008, 30(4): 560-565.
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)
PDF(2303 KB)
