北疆坝基盐渍化粉土变形特性影响试验研究

    Experimental study on influences of deformation characteristics of salinized silty soil at dam base in northern Xinjiang

    • 摘要: 针对北疆地区广泛分布的一种盐渍化粉土开展了压缩和增湿变形试验研究。试验结果显示,盐渍化粉土的固结及增湿变形与非含盐土具有显著区别,其中压缩特性受干密度的影响较小,受含水率及含盐量的影响较大。其它条件一定时,含水率7.8%时试样的压缩模量Es1-2为46.10 MPa,饱和试样的压缩模量Es1-2降至9.75 MPa;而相较非盐渍化粉土,含盐量为6.4%的盐渍化粉土其压缩模量Es1-2由32.11 MPa将降至14.89 MPa。另一方面,低围压条件下含盐量变化对盐渍化粉土的增湿变形有显著影响。无上覆荷载时试样含盐量越高,土样的增湿膨胀率越大,此时硫酸盐的存在“促进”了土壤的膨胀变形;当固结荷载大于25 kPa时,含盐量对膨胀率的影响由正相关变为负相关,此时含盐量的增加反而抑制了膨胀变形,甚至导致土样出现压缩变形。相关性分析表明, 除去上覆应力外,含水率、含盐量的变化程度均是盐渍化粉土的固结变形特性的主要影响因素,同时含盐量对于盐渍化粉土增湿变形的影响更加明显。

       

      Abstract: For the deformation characteristics of a kind of salinized silty soil widely distributed in the northern Xinjiang area, the compression and humidification deformation tests are carried out. The test results show that the compression characteristics of salinized silty are less affected by dry density and more affected by water content and salt content. When other conditions are constant, the compressive modulus Es1-2 of the sample is 46.10 MPa when the water content is 7.8%, and that of the saturated sample is 9.75 MPa. When other conditions are constant, the compression modulus Es1-2 of the saline-washed soil sample is 32.11 MPa, and that of the salt content is 14.89 MPa. On the other hand, the change of salt content under low perimeter pressure has a significant effect on the moisture-enhancing deformation of the salinized silt. In the case of no load, the higher the salt content, the greater the swelling rate of the soil samples, and the presence of sulfate promotes the swelling of the soil. When the consolidation load is greater than 25 kPa, the effects of salt content on the swelling rate change from a positive correlation to a negative one, and at this time the increase in the salt content instead of suppression of the swelling, and even lead to the compression deformation of the soil samples. The correlation analysis shows that, except the overlying stress, the water content is the main influencing factor for the compression characteristics of the salted silt, and the salt content has more obvious influences on the humidification and deformation of the salted chalk.

       

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