路用砂类盐渍土盐胀及融陷特性试验研究

砂类硫酸盐及亚硫酸盐渍土广泛分布于中国西部地区,研究其作为路堤填料的可用性,可充分利用当地资源和节约建设资金。以路基填筑标准及合理的防排水设施为前提条件,基于5 mm筛法配制盐分,研究了不同含盐量水平下砂类盐渍土的盐胀变化特点和在冻融循环作用下砂类盐渍土体的融陷特性,试验结果表明:砂类亚硫酸盐渍土比砂类硫酸盐渍土的盐胀起胀温度和敏感温度区间低约5℃;对于4砂类硫酸盐渍土,含盐量不大于1%时,盐胀率小于1.5%;对于砂类亚硫酸盐渍土,含盐量小于2.3%~2.5%时,盐胀率小于1%;在冻融循环作用下,砂类亚硫酸盐渍土具有较强的融(溶)陷特性;路面容许变形量取2 cm,下路堤填筑厚度为2.0 m时,砂类硫酸盐渍土的含盐量极限值为1.0%,砂类亚硫酸盐渍土的含盐量极限值为2.3%。

Experimental study on salt expansion and thawing subsidence properties of sandy saline soil

In Northwest China, there is a large amout of sandy sulphate and sulfite saline soil. This saline soil can be used as embankment fill, which can make full use of local resources and save construction cost of highways. Taking the subgrade filling standards and reasonable drainage facilities as the prerequisite conditions, based on the soluble salt content preparation method of screening method of 5 mm, the salt expansion change characteristics of sandy saline soil from the single cooling tests and the thawing subsidence characteristics of sandy saline soil from the experiments on freeze-thaw cycles are studied under different salinity levels. It is shown that the inception temperature and sensitive temperature range of the sandy sulfite saline soil are 5℃ lower than those of the sandy sulphate saline soil. When the salt content is less than 1%, the salt expansion rate of sandy sulphate saline soil is less than 1.5%. When the salt content is less than 2.3%~2.5%, the salt expansion rate of sandy sulfite saline soil is less than 1.0%. Under several freez-thaw cycles, the sandy sulfite saline soil has strong thawing subsidence characteristics. Under the conditions of allowable deformation of pavement being 2 cm and embankment thickness 2.0 m, the limit of sandy sulphate saline soil is 1.0% and the limit of sandy sulfite saline soil is 2.3% for subgrade fill.