蒸发作用下盐渍土路基换土填层水盐迁移规律研究  

Study on Water-salt Migration Rule of Replacement of Soil on Saline Soil Subgrade under Evaporation

作　　者：杨熙 王英 李萍[1] YANG Xi;WANG Ying;LI Ping(School of Civil Engineering,Lanzhou University of Technology,Lanzhou Gansu 730050,China)

机构地区：[1]兰州理工大学土木工程学院,甘肃兰州730050

出　　处：《公路交通科技》2023年第7期68-77,共10页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(51868047);甘肃省自然科学基金项目(21JR7RA273);甘肃省优秀研究生“创新之星”项目(2021CXZX-492);兰州理工大学研究生科研探索项目(256017)。

摘　　要：为了解决夏季西北盐渍土地区路基表层盐分积聚现象明显的现状,基于甘肃武威硫酸盐渍土地区的道路水温环境,采用自主设计的室内盐渍土水盐迁移装置,探究了蒸发作用下不同掺砂率的“黄土+砂”盐渍土路基换土填层的水盐迁移规律,从而进一步评价了盐渍土路基换土填层的处置效果。结果表明:在常温条件下,当掺砂率小于30%时,随着掺砂率的增大,水盐迁移速率增大,最大迁移高度位于土柱的中部区域;当掺砂率达到30%时,水盐迁移的高度和速率最高,最大迁移高度位于土柱的中上部区域;当掺砂率增加至50%时,水盐迁移速率显著下降,最大迁移高度位于土柱中下部区域;在强蒸发环境下,随着温度的升高及温度循环次数的增加,不同掺砂率条件下的换土填层土柱受到毛细作用和温度梯度的双重激励,水盐迁移速率较常温条件呈现不同幅度的增加;掺砂率越高,水盐迁移速率增幅越小,温度对土样盐分分布的影响作用越小,盐分主要集聚于土柱的中上层区域。采用“黄土+砂”的换土填层,可有效抑制盐分在土中的迁移速率,盐分与水分的整体变化可表现为“盐随水动”的特点,当掺砂率大于50%时,换土填层的水盐迁移的速率降低,迁移高度下降,对盐分的抑制效果最显著。In order to solve the current situation of obvious salt accumulation on the surface layer of subgrade in the saline soil region of northwest China in summer,based on the road water temperature environment in the sulfate saline soil region of Wuwei in Gansu,by using the self-designed indoor water-salt migration device,the water-salt migration rule of replacement of soil on the"loess+sand"saline soil subgrade with different sand ratios under evaporation is explored,and the disposal effect of replacement of soil on saline soil subgrade is further evaluated.The result shows that(1)at normal temperature,when the sand ratio is less than 30%,the water-salt migration rate increases with the increase of sand ratio,and the maximum migration height is located in the middle of the soil column;(2)when the sand ratio reaches 30%,the height and rate of water-salt migration are the highest with the maximum migration height located in the upper and middle parts of the soil column;(3)when the sand ratio increases to 50%,the water-salt migration rate decreases significantly,and the maximum migration height is located in the middle and lower parts of the soil column;(4)under a strong evaporation environment,with the increase of temperature and the number of temperature cycles,the soil columns of the replacement of soil under different sand ratio conditions are dual motivated by capillarity and temperature gradient,and the water-salt migration rates show different degrees of increase compared with those under normal temperature condition;(5)the higher the sand ratio,the smaller the increase of water-salt migration rate,and the less the influence of temperature on the distribution of salt in soil samples,the salt is aggregated in the upper and middle parts of column mainly.The migration rate of salt in the soil can be inhibited effectively by using"loess+sand"replacement of soil,and the overall change of salt and water can be characterized as"salt moving with water".When the sand ratio is more than 50%,the rate of water-salt migration

关 键 词：道路工程 水盐迁移 模型试验 掺砂率 电导率 蒸发作用 

分 类 号：TU448[建筑科学—岩土工程]