煤气化粗渣改良季节冻土区黄土填料的冻融特性及其微观机理研究  

Freeze-thaw characteristics and microscopic mechanism of coarse coal gasification slag improved loess filler

作　　者：武立波[1,2] 杨嘉伟 刘惠阳 陈宏信 WU Libo;YANG Jiawei;LIU Huiyang;CHEN Hongxin(School of Civil Engineering and Water Conservancy,Ningxia University,Yinchuan 750021,China;Key Laboratory of Geotechnical and Underground Engineering,Ministry of Education,Tongji University,Shanghai 200092,China)

机构地区：[1]宁夏大学土木与水利工程学院,宁夏银川750021 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《冰川冻土》2024年第3期930-943,共14页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(41961011);2023年度宁夏回族自治区留学回国人员创新项目“煤基固废改良黄土的力学性能和抗冻性研究”;同济大学岩土及地下工程教育部重点实验室开放基金项目(KLE-TJGE-B2302)资助。

摘　　要：由于周期性的冻融循环作用,中国西北黄土区路基工程极易发生冻融病害,常用的解决方法是用改良黄土作为路基填料。目前工业废弃物改性不良路基土已成为工程地基改良处理的新趋向,鉴于西北地区煤气化渣堆存量巨大且资源化利用率低,尝试用煤气化粗渣改良季节冻土区黄土,以素黄土与单掺石灰改良黄土作为对比试验组,通过室内冻融循环试验、电镜扫描、CT扫描试验来探究在冻融循环条件下煤气化粗渣改良黄土的冻融特性及其微观机理,为季节冻土区黄土路基工程稳定性及煤气化渣资源化利用提出一些新的思考。试验结果表明:(1)经历1次与2次冻融循环后,单掺15%煤气化粗渣试验组的冻胀率为0.02%与0.29%,融沉系数为0%与0.05%,素黄土、单掺4%石灰试验组的冻胀率分别为0.43%与0.63%、0.38%与0.42%,融沉系数分别为0.26%与0.22%、0%与0.13%,但在经历3次冻融循环后,单掺15%煤气化粗渣试验组的冻胀率和融沉系数开始增大,5次冻融循环周期内的平均冻胀率和融沉系数分别为0.38%与0.17%,已接近甚至大于素黄土与单掺4%石灰试验组的数值。在前两次冻融循环周期内,平均冻胀率和融沉系数较素黄土组分别减小了70.8%和89.6%。(2)单掺15%煤气化粗渣试样各位置的温度梯度最小,其次是双掺煤气化粗渣与石灰试样,并且这两组试样正负温条件下的导热系数最小。(3)经过5次冻融循环后,单掺15%煤气化粗渣试样各高度的含水率最低。(4)单掺适量的煤气化粗渣在冻融循环的初期能明显地改善黄土的冻融特性,再掺入少量的石灰能使试样在冻融循环前后的孔隙率较素黄土分别降低41.5%与47.8%。总的来说,黄土中掺入煤气化粗渣在冻融循环次数少于3次时能改善黄土路基填料的寒区服役性,但其在更多次冻融循环条件下的冻融特性还需进一步研究。In the loess area of northwest China,the subgrade engineering is facing the problem of freeze-thaw diseases owing to the freezing-thawing cycles.A commonly prevention method is using the improved loess as subgrade filling,and now the approach of poor subgrade soil improved by the industrial waste has become a new trend of ground treatment.Considering a huge stock of coal gasification slag and their low utilization rate,and coal gasification slag needs to be immediately treated safely and reasonably.Thus,we proposed a new approach of using the loess improved by the coal gasification slag as subgrade filling in seasonal frozen ground regions,and our previous studies have shown that a certain amount of coal gasification coarse slag improved loess as sub-grade filler is suitable for mechanical properties.In this study,the freeze-thaw characteristics and microscopic mechanism of coal gasification coarse slag modified loess under freeze-thaw cycle conditions were explored through laboratory freeze-thaw cycle tests,electron microscope scanning and CT scanning tests,and the two groups of pure loess and single lime modified loess were tested as comparison groups.The experimental results show that:(1)After the first and second freezing-thawing cycles,the frost-heave ratios of the group of mixing 15%coarse coal gasification slag were 0.02%and 0.29%,and the thaw-settlement coefficients were 0 and 0.05%.The frost-heave rates of the groups of pure loess and with 4%lime were 0.43%and 0.63%,0.38%and 0.42%,respectively.The thaw-settlement coefficients were 0.26%and 0.22%,and 0 and 0.13%,respective-ly.However,after three times of freeze-thawing cycles,the frost-heaving ratio and the thaw-settlement coeffi-cient of the experimental group with only 15%coarse coal gasification slag began to increase,and the average frost-heaving rate and the thaw-settlement coefficient during five freezing-thawing cycles were 0.38%and 0.17%,respectively.It is close to or even greater than the values of the experimental groups of pure loess and mixing

关 键 词：季节冻土区 煤气化粗渣 黄土 路基填料 冻融特性 微观机理 

分 类 号：P642.14[天文地球—工程地质学] U419.92[天文地球—地质矿产勘探]