基于混合物理论的非饱和土的热-水-力耦合分析模型Ⅰ

以混合物理论为基础研究了非饱和土的热-水-力多场耦合问题.将非饱和土视为由土骨架、液态水、水蒸气、干燥气体及溶解气体共5种组分构成的混合物,在组分的质量、动量守恒方程及整体能量守恒方程的基础上,引入了37个补充方程以形成封闭方程组.其中,利用水与水蒸气的化学势改变量相同,推导了在气压力变化条件下水与水蒸气相变平衡所满足的限制方程.最终控制方程以增量形式给出,6个方程求解6个未知量(3个土骨架位移、水压力、气压力及温度),充分反映了热膨胀、热渗流、水的相变、气体溶解及土骨架变形等多种现象的耦合过程.     

生物修复放射性污染土壤的研究进展

核能的利用给人类带来了福利也带来了灾难。部分土壤被放射性物质污染,放射性物质通过食物链进入人体,威胁人类健康。目前各国科研工作者正在积极寻找可行的办法解决土壤的放射性污染问题,并发展起来许多方法来修复放射性污染的土壤。本文就放射性污染土壤的来源、危害、处理等进行综述,并重点介绍了生物修复放射性污染土壤的研究进展。     

Analysis of coupled thermo-hydro-mechanical behavior of unsaturated soils based on theory of mixtures I

This paper analyzes a coupled thermo-hydro-mechanical behavior of unsaturated soils based on the theory of mixtures. Unsaturated soil is considered as a mixture composed of soil skeleton, liquid water, vapor, dry air, and dissolved air. In addition to the mass and momentum conservation equations of each component and the energy conservation equation of the mixture, the system is closed using other 37 constitutive （or restriction） equations. As the change in water chemical potential is identical to the change in vapor chemical potential, a thermodynamic restriction relationship for the phase transition between pore water and pore vapor is formulated, in which the impact of the change in gas pressure on the phase transition is taken into account. Six final govern- ing equations are given in incremental form in terms of six primary variables, i.e., three displacement components of soil skeleton, water pressure, gas pressure, and temperature. The processes involved in the coupled model include thermal expansions of soil skeleton and soil particle, Soret effect, phase transition between water and vapor, air dissolution in pore water, and deformation of soil skeleton.     

特选榨菜对铀污染土壤的修复评价

本文通过两种不同的加铀方式,加入不同种类及浓度的螯合剂,以及土壤改良剂(有机肥、微生物肥料、腐殖酸、尿素)的方法,研究了不同因素对特选榨菜修复铀污染土壤的影响。结果表明:在pH=5时把UO_2(NO_3)_2·6H_2O溶液喷洒入土壤,使土壤中铀污染浓度为100 mg·kg~(-1)时,特选榨菜地上部铀富集的浓度最大可以达到1103.42 mg·kg~(-1),根部为1909.49 mg·kg~(-1),去除率为7.81%;上述含铀土壤放置2年后制备成模拟铀污染的土壤,进而栽种特选榨菜进行修复,在100 mg·kg~(-1)铀污染浓度下,植物上部铀富集浓度最大为295.83 mg·kg~(-1),根部为268.42 mg·kg~(-1),年去除率为2.52%。用Tessier五步连续提取法测定两次修复土壤中铀的形态,发现模拟铀污染土壤比铀喷洒于土壤中有效态的铀(交换态和碳酸盐结合态)要低52.7%;加入柠檬酸、苹果酸等螯合剂以及有机肥、微生物肥料、腐殖酸、尿素等土壤改良剂,在模拟铀污染土壤修复时发现有机肥会降低植物上部对铀的富集;而柠檬酸和微生物肥会增强植物上部对铀的富集。