摘要
为了明确含泥量对砂类硫酸盐渍土的盐胀和力学特性的影响,人工配制了不同细粒土含量的砂类硫酸盐渍土,在1%和3%(质量分数,下同)含盐量单向冻结盐胀试验的基础上,选取了细粒土含量为5%、15%、30%和40%的砂样进行常温、低温三轴剪切试验。研究结果表明:此试验条件下,不同级配砂类硫酸盐渍土的冻结温度为-0.7~-0.1℃,当砂样孔隙溶液浓度在冻结温度之上达到饱和时,降温过程中会首先生成盐结晶;1%含盐量条件下,高细粒土含量(≥30%)砂样的起胀温度在4~9℃之内,而低细粒土含量砂样的起胀温度在0℃附近,3%含盐量砂样的起胀温度为20~23℃;试验含水率和细粒土含量通过影响土体中自由水的含量对盐冻胀产生显著影响。在力学特性方面,随着细粒土掺量的增加,砂类硫酸盐渍土的抗剪强度表现出先增大后减小的趋势,细粒土由增强摩擦转变为颗粒间的“润滑”作用;此外,冻结后砂土转变为承载能力更强的“土-盐-冰骨架结构”,抗剪强度大幅提高,并呈现出明显的脆性破坏特征,由于冻结砂土受相对温度的影响,随着含盐量的增加,破坏应力呈先减小后增大的趋势。
In order to study the influence of mud content on salt swelling and mechanical properties of sand sulfate soils,sand sulfate soils with different fine-grained soil content were manually configured.Based on the unidirectional freezing salt swelling test with 1%and 3%salt content,sand samples with fine-grained soil mass fraction of 5%,15%,and 30%were selected to conduct triaxial shear tests at constant and low temperature.The results showed that with the conditions of this test,the freezing temperature of sand sulfate saline soil of different levels was within the range of-0.7--0.1℃.When the pore solution concentration of the soil samples reached saturation above the freezing temperature,salt crystals could first be generated in the cooling process.With the condition of 1%salt content,the initial swelling temperature of sand samples with high fine-grained soil content(≥30%)was in the range of 4-9℃,while the initial swelling temperature of sand samples with low fine-grained soil content was near 0℃.The swelling temperature of 3%salt content sand sample was 20-23℃.The process of salt frost heave was inseparable from the participation of free water.The test water content and fine-grained soil content had a significant effect on salt frost heave by influencing the content of free water in the soil.In terms of mechanical properties,with the increase of the content of fine-grained soil,the shear strength of sand sulfate soils increased first and then decreased,and the fine-grained soil changed from enhancing friction to"lubrication"between particles.In addition,after freezing,the sand was transformed into a"soil-salt-ice skeleton structure"with a stronger bearing capacity,and the shear strength increased greatly,showing obvious brittle failure characteristics.Affected by relative temperature,the failure stress of frozen sand decreased first and then increased with the increase of salt content.
作者
张莎莎
张超
王旭超
赵彦虎
ZHANG Shasha;ZHANG Chao;WANG Xuchao;ZHAO Yanhu(School of Highway,Chang′an University,Xi′an 710064,China)
出处
《郑州大学学报（工学版）》
北大核心
2024年第1期98-106,共9页
Journal of Zhengzhou University（Engineering Science）
基金
国家自然科学基金资助项目(42101126)
青海省交通运输厅科技项目(2020-02)。
关键词
砂类土
盐渍土
盐胀试验
三轴剪切试验
细粒土含量
SEM试验
sand soil
saline soil
salt swelling test
triaxial shear test
fine-grained soil content
SEM test
