兰州大学机构库 >土木工程与力学学院
非饱和土在直流电场作用下水分分布研究
Alternative TitleMoisture Redistribution in the Unsaturated Soil Subjected to DC Electric Field
杨冰卓
Thesis Advisor张虎元
2017-05-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword遗址保护 非饱和土 直流电场 水分分布
Abstract

非饱和土中水分的迁移主要是在基质势和重力势的共同驱动下产生的。受毛细上升作用的影响,潮湿土遗址中发生水分运移及含水率波动,导致一系列干缩开裂、盐害等问题,促进土遗址的劣化。本论文研究直流电场控制毛细水上升的学术机理,探讨向土体施加直流电场抑制潮湿土遗址中毛细水上升的可行性。

本论文从非饱和土中能量状态分析出发,基于非饱和达西定律、欧姆定律、电荷守恒定律以及质量守恒定律,建立了描述非饱和土在直流电场作用下的水分分布的理论模型,并具体讨论了模型中涉所及的参数(如土体电导率、基质吸力以及非饱和渗透系数)与含水率的关系。

利用室内的直流电场抑制毛细水上升试验数据,检验了直流电场作用下的水分分布理论模型的可靠性。测定土水特征曲线、土体的非饱和渗透系数,获得理论模型所包含的参数;以具体试验情况为基础,设定初始条件和边界条件,实现理论计算结果与试验结果的对比。

本论文阐述了毛细水与土遗址劣化的关系,分析了施加直流电场抑制毛细水上升进而保护土遗址的原理。研究认为,土遗址的劣化,不是水分本身造成的,而是在毛细水作用下含水率的变化及盐分的运移造成的。施加直流电场,能够通过电势来削弱基质势引起的毛细水迁移问题。

研究发现,直流电场作用下的水分分布的理论模型,理论计算结果与试验结果吻合良好,能够定量地描述直流电场对毛细水运移的影响。研究结果表明,直流电场通过抑制非饱和土中毛细水运移,能够有效减少遗址土中水分波动,进而减少遗址土湿胀-干缩和盐分反复溶解-结晶,达到保护土遗址的目的。

Other Abstract

Water migration in unsaturated soil is mainly driven by matric potential and gravity potential. With respect to an earthen site in moist circumstances, it is the moisture content fluctuation and water migration involved with capillarity that lead to the deterioration of the heritage, such as dry shrinkage and salt weathering. This thesis studies the mechanism that applying direct current field to control capillary water rise in soil. So to investigate the feasibility of conserve a heritage with DC in moist circumstances.

Primarily, this thesis analyzed the energy state, and established a theoretical model, describing the moisture redistribution in unsaturated soil subjected by DC electric field, based on Darcy’s law, Ohm’s law, law of conservation of charge and law of conservation of mass. Furthermore, the relevant parameters included in this model were discussed in detail, such as electrical conductivity, unsaturated permeability coefficient and matric suction to be responsible to soil moisture content.

Both the results between laboratory test and theoretical calculation have been compared to verify the reliability of the moisture redistribution model in unsaturated soil. The soil-water characteristic curve (SWCC) and the unsaturated infiltration coefficient were measured to obtain the parameters required for the theoretical calculation. And initial and boundary conditions were set up following the laboratory test conditions for the theoretical calculation.

This thesis discussed,the relationship between capillary water and the deterioration of the soil site so to highlight the principle that heritage site can be protected by applying DC to restrain capillary rise. Research results prove that earthen site deterioration is attributed to moisture content fluctuation and salt migration rather than water itself. Therefore, DC electric field can be applied to restrain capillary migration generated by soil matrix potential.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226543
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
杨冰卓. 非饱和土在直流电场作用下水分分布研究[D]. 兰州. 兰州大学,2017.
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