Effects of compaction and water content on thermal conductivity of unsaturated soils
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摘要: 土体的导热系数是地下空间结合地热能开发等岩土工程重要的热物理参数。现场土往往处于非饱和状态,研究其导热性能有重要工程价值。采用瞬态法测量了不同压实度和含水率下非饱和石英砂、石英粉和高岭土的导热系数,研究这3种非饱和土体的导热系数与含水率和干密度的关系。研究结果表明,在相同压实度下,石英砂、石英粉和高岭土的导热系数在临界含水率之前随着含水率的增加而快速增加,之后增势变缓趋于稳定;临界含水率从大到小依次为:高岭土、石英粉、石英砂;在相同压实度和含水率下,石英砂的导热系数最大,石英粉次之,高岭土最小;相同含水率时,3种土体的导热系数均随干密度的增加而线性增加。Abstract: The thermal conductivity of soils is an important thermal physical parameter for geotechnical engineering such as underground space and geothermal development. Field soils are generally under unsaturated state, and studying on the thermal conductivities of unsaturated soils has important engineering value. The thermal conductivities of quartz sand, quartz powder and kaolin clay under different degrees of compaction and different water contents are measured by using the transient state method, and the relationships between thermal conductivities of the three unsaturated soils with water content and dry density are studied. The results show that under the same degree of compaction, the thermal conductivities of quartz sand, quartz powder and kaolin clay all increase rapidly with the increase of water content before critical water contents, and then tend to be stable. The critical water content of kaolin clay is the highest, followed by quartz powder and then quartz sand. Under the same degree of compaction and the same water content, the thermal conductivity of quartz sand is the largest, followed by quartz powder and then kaolin clay. Under the same water content, the thermal conductivities of the three soils all increase linearly with the increase of dry density.
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Keywords:
- unsaturated soil /
- thermal conductivity /
- degree of compaction /
- water content
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表 1 试验用土的基本参数
Table 1 Basic properties of test soils
土类 类型 最大干密度/(g·cm-3) 最优含水率/% 饱和含水率/% 石英砂(20目) 砂土 1.68 19 25 石英粉(200目) 粉土 1.68 19 30 石英粉(500目) 粉土 1.68 19 40 高岭土(800目) 黏土 1.29 37 45 表 2 试验方案
Table 2 Test programs
编号 土类 压实度/% 质量含水率/% 1-6 石英砂 (20目) 80 0,10,15,20,25,饱和 7-12 90 13-18 100 19-23 石英粉 (200目) 80 10,15,20,25,30(饱和) 14-28 90 29-33 100 34-38 石英粉 (500目) 80 10,15,20,25,40(饱和) 39-43 90 44-48 100 49-54 高岭土 (800目) 80 20,25,30,35,40,45 55-60 90 61-66 100 -
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