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基于气体分子动理论的土壤孔隙结构特征研究
孙义亨, 施少敏, 宋学姝, 孟平, 张劲松, 任荣秀, 陆森
中国林业科学研究院林业研究所, 北京 100091
摘要:
通过测定两种土壤和一种玻璃珠的两相热导率随气压的变化,分析变压条件下气体分子碰撞平均自由程和多孔介质孔隙结构间的关系。研究计算了表征土壤平均孔隙结构的孔隙特征长度(d),同时依据静态几何学方法计算获取了颗粒平均间距(D)。结果表明,基于热传输方法获取的d值是从气体分子碰撞传热的动态观点获取的孔隙结构表征,标识着土壤颗粒间的热分离特征,是表征土壤孔隙结构的有效指标。由于土壤的dD值相差3个数量级,但在玻璃珠上无量级差异,这说明d值可能只能表征土壤团聚体间的平均孔隙结构,不能反映团聚体内部及黏土颗粒内部的微细孔隙结构。
关键词:  土壤  孔隙结构  热导率  气体分子动理论
DOI:10.13758/j.cnki.tr.2021.02.025
分类号:S152.8
基金项目:中国林科院院基金项目(CAFYBB2017QC001)和国家自然科学基金项目(41877019)资助。
Study on Soil Pore Structure with Kinetic Molecule Theory of Gases
SUN Yiheng, SHI Shaomin, SONG Xueshu, MENG Ping, ZHANG Jinsong, REN Rongxiu, LU Sen
Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
Abstract:
In this study, the two-phase thermal conductivity of two soils and a glass bead under various pressures was measured. The relationship between pore structure of porous media and mean free path of air molecular was investigated. The characteristic dimension of gas space among particles (d) representing soil average pore structure was calculated. Moreover, static mean separation of particles (D), i.e., geometric mean dimension of gas space among particles was also calculated. d value obtained based on heat transfer method reflects the collision process of gas molecules and solid particles in soil pores. The results showed that d represents the thermal separation characteristics among solid particles, and is an effective index to characterize soil pore structure. There are three orders of magnitude difference between soil d and D values. However, there is no order of magnitude difference on glass bead. d value may only represent average pore structure of inter-aggregates, and cannot reflect fine pore structures of intra-aggregates and clay particles.
Key words:  Soils  Pore structure  Thermal conductivity  Kinetic theory of gases

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