This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under di...This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under different drying temperatures and relative humidity are carried out in a constant climate chamber. Then, the undisturbed samples, prepared in different drying environment, are used for the triaxial tests and mercury intrusion tests. It is found that the drying environment has noticeable influence on the engineering properties of expansive soils and it can be characterized by the drying rate. The linear shrinkage and strength increase with the decrease of the drying rate. The non-uniform deformation tends to happen in the high drying rate, which subsequently furthers the development of cracks. In addition, during the drying process, the variation of pores mainly focuses on the inter-aggregate pores and inter-particle pores. The lower drying rate leads to larger variation of pore size distribution.展开更多
In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the developm...In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the column.When a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.展开更多
选择位于季风边缘区的吉兰泰盐湖为研究对象,利用OSL和14C测年手段重建湖面波动历史,探讨盐湖形成年代与环境变化过程。通过大范围的野外调查发现,在该湖泊南部地区发育高于现代干盐滩9 m的湖滨砂沉积,上覆风成砂沉积,其中湖滨沉积物的...选择位于季风边缘区的吉兰泰盐湖为研究对象,利用OSL和14C测年手段重建湖面波动历史,探讨盐湖形成年代与环境变化过程。通过大范围的野外调查发现,在该湖泊南部地区发育高于现代干盐滩9 m的湖滨砂沉积,上覆风成砂沉积,其中湖滨沉积物的OSL年代为6.7 ka BP前后,表明当时该湖泊处于浅水状态,此后湖水经历了快速的下降过程。对于盐湖中心剖面点盐层之下粘土层的14C测年显示,在5 500 aBP以来,集聚大量的石膏、芒硝和石盐等蒸发盐类,该湖泊进入成盐期。通过区域对比发现,吉兰泰湖面快速下降阶段与季风边缘区中全新世干旱事件发生时间相对应。研究认为,吉兰泰盐类矿物的开始沉积,反映了中全新世阿拉善高原区域环境的突然变化,可能指示着5.5 Cal ka BP前后干旱事件的发生。展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 41430634)the State Key Laboratory of Geomechanics and Geotechnical Engineering (Grant No. Y11002)
文摘This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under different drying temperatures and relative humidity are carried out in a constant climate chamber. Then, the undisturbed samples, prepared in different drying environment, are used for the triaxial tests and mercury intrusion tests. It is found that the drying environment has noticeable influence on the engineering properties of expansive soils and it can be characterized by the drying rate. The linear shrinkage and strength increase with the decrease of the drying rate. The non-uniform deformation tends to happen in the high drying rate, which subsequently furthers the development of cracks. In addition, during the drying process, the variation of pores mainly focuses on the inter-aggregate pores and inter-particle pores. The lower drying rate leads to larger variation of pore size distribution.
基金the University of Ottawa and the National Natural Sciences and Engineering Research Council of Canada(NSERC)for supporting this research
文摘In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the column.When a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.
文摘选择位于季风边缘区的吉兰泰盐湖为研究对象,利用OSL和14C测年手段重建湖面波动历史,探讨盐湖形成年代与环境变化过程。通过大范围的野外调查发现,在该湖泊南部地区发育高于现代干盐滩9 m的湖滨砂沉积,上覆风成砂沉积,其中湖滨沉积物的OSL年代为6.7 ka BP前后,表明当时该湖泊处于浅水状态,此后湖水经历了快速的下降过程。对于盐湖中心剖面点盐层之下粘土层的14C测年显示,在5 500 aBP以来,集聚大量的石膏、芒硝和石盐等蒸发盐类,该湖泊进入成盐期。通过区域对比发现,吉兰泰湖面快速下降阶段与季风边缘区中全新世干旱事件发生时间相对应。研究认为,吉兰泰盐类矿物的开始沉积,反映了中全新世阿拉善高原区域环境的突然变化,可能指示着5.5 Cal ka BP前后干旱事件的发生。
