冻融循环作用下硫酸盐盐渍土物理力学特性试验研究
Experimental study on mechanical properties of sulfate saline soil under freeze-thaw cycle
何野1
作者信息
- 1. 中铁十九局集团 第三工程有限公司,辽宁 沈阳 110136
- 折叠
摘要
为研究硫酸盐盐渍土在冻融循环作用下的力学特性,结合京沈高速铁路朝阳段的工程实际,利用三轴不固结不排水试验对不同冻融循环次数(最多 50 次)、盐质量分数(0%、2%和5%)和围压(100 kPa、200 kPa、300 kPa和400 kPa)下的硫酸盐盐渍土进行研究,分析不同试验条件下硫酸盐盐渍土的抗剪强度特性及强度劣化机理.研究结果表明:随着冻融循环次数、盐质量分数和围压的逐渐增加,硫酸盐盐渍土的应力-应变曲线逐渐由应变软化向应变硬化转变;抗剪强度随冻融循环和盐质量分数的增加而逐渐降低;对于盐质量分数 0%的试样,内摩擦角受冻融循环影响不明显,在30°～34°之间;在短期冻融循环(1～9 次)作用下,黏聚力呈上升趋势,在冻融循环9～20 次过程中,黏聚力急剧下降,当冻融循环大于 20 次后,黏聚力逐渐趋于稳定;对于盐质量分数 2%和 5%的试样,短期冻融循环(小于 9 次)对内摩擦角影响不显著,而在冻融循环 20 次后,内摩擦角急剧减小;在冻融循环 1～20 次过程中,试样的黏聚力逐渐减小,在冻融循环 20 次时,黏聚力达到最小值;土样在反复冻融循环作用后,土体颗粒大量分解,粒度逐渐变细,细颗粒占比逐渐增大.研究结果可为类似工程提供理论指导.
Abstract
In order to study the mechanical properties of sulphate saline soil under freeze-thaw cycle,triaxial unconsolidated undrained test(UU)was used to study sulphate saline soils with different freeze-thaw cycles(up to 50),salt mass fraction(0%,2%and 5%),and confining pressures(100 kPa,200 kPa,300 kPa and 400 kPa)in conjunction with the engineering practice of the Chaoyang section of the Beijing-Shenyang high-speed Railway,.The analysis focused on the shear strength characteristics and strength deterioration mechanism of the sulphate saline soil under varying test conditions.The results show that the stress-strain curve of the sulfate saline soil gradually changes from strain softening to strain hardening with the increase of the number of freeze-thaw cycles,salt content fraction,and confining pressure.The shear strength decreases with increased freeze-thaw cycles and salt content.For samples with 0%salt content,the internal friction angle is not significantly affected by freeze-thaw cycle,and ranges from 30° to 34°.Under short-term freeze-thaw cycle(n=1～9),cohesion showed an upward trend,while during the 9～20 freeze-thaw cycles,cohesion decreased sharply and gradually stabilized after 20 cycles.For samples with 2%and 5%salt content,the influence of short-term freeze-thaw cycle(n＜9)on the internal friction angle is not significant,but the internal friction angle decreases sharply after 20 cycles.In the process of 1～20 freeze-thaw cycles,the cohesion of the sample decreases gradually,reaching the minimum value at 20 cycles.Following repeated freeze-thaw cycles,soil particles decompose in large quantities,leading to a gradual decrease in particle size and an increase in the proportion of fine particles.The research results can provide theoretical guidance for similar projects.
关键词
硫酸盐盐渍土/三轴试验/冻融循环/含盐量/抗剪强度参数Key words
sulfate saline soil/triaxial test/freeze-thaw cycle/salt content/shear strength parameters引用本文复制引用
出版年
2024
NETL
NSTL
维普
万方数据