冻融循环条件下亚氯盐渍土盐冻胀试验研究

为研究亚氯盐渍土的盐冻胀特性,对罗布泊地区天然亚氯盐渍土进行多次冻融循环试验,研究了含硫酸盐亚氯盐渍土的温度变化规律和盐胀特性。试验结果表明:在冻融循环作用下,同一土层的温度升降基本一致,每一土层的温度分布形式成抛物线型,离冷端面较近的第1层和第2层温度变化较大,而第3层到第5层温度变化较小;低液限粉土的亚氯盐渍土具有较好的盐胀累加效果,盐胀量随着温度的降低而增加,随着温度的升高有所回落,最大盐胀量可达到7.61 mm;前4周期的盐胀效果明显,产生的盐胀量约占总盐胀量的80%;盐胀在前6次冻融循环逐渐增大,但增大的趋势慢慢降低,并在第7次冻融循环作用时趋于稳定。研究成果可为分析含硫酸盐亚氯盐渍土的盐胀机理和治理盐胀病害提供参考。

Salt Heaving Test of Sub-chlorine Saline Soil under Cyclic Freezing and Thawing

The temperature variation and salt expansion characteristics of natural sub-chlorine saline soil in Lop Nur under cyclic freezing and thawing are investigated. Test results show that under the action of cyclic freezing and tha-wing,the temperature fluctuation in a same soil layer keeps consistent;temperature distributes in a parabolic shape as freezing and thawing cycle proceeds, with the first and the second layers near the cold end surface undergoing great temperature changes while the third layer to the fifth layer experiencing small temperature change. Sub-chlo-rine saline soil with low liquid limit silt has a good effect of salt expansion and accumulation;the salt expansion in-creases as temperature declines,and vice versa,with the maximum salt expansion reaching 7.61 mm. In the first four periods (cycles), the salt heaving effect is obvious, and the salt expansion amount is about 80% of the totalsalt expansion. Salt expansion in the first six freeze-thaw cycles increases gradually, but the trend slowly attenuates,and tends to be stable in the seventh freeze-thaw cycles.