基于CT的南方湿热地区红粘土路基水—汽迁移研究

发布时间：2018-06-01 06:41

本文选题：CT分析技术 + 南方湿热地区　；参考：《长沙理工大学》2014年硕士论文

【摘要】：现有道路路基病害修复和调查表明,路基病害的发生无不与路基内部湿度状况有关,尤其是路基中水-汽迁移引起含水率显著偏离路基设计时设定的湿度状态,从而导致道路整体承载力下降和累计永久变形持续增大,并由此引发道路病害。目前,国内外研究水-汽迁移的学者相继增多,但其对含水率的测定一般采用烘干法或单点埋设含水率测定计,导致测定具有一定的不连续性、偏低性及不均匀性,对研究路基土水-汽迁移规律造成一定程度的影响。由于X射线具有非破坏,非侵入的性质,CT分析技术能在不扰动土体的同时,提供揭示水-汽在土体中的流动行为和机制的线索。本论文采用CT分析技术研究南方湿热地区红粘土路基水-汽迁移规律。论文首先通过JTG E40-2007《公路土工试验规程》的T0130一一变水头渗透试验得出了红粘土样93%压实度11.30C和标准温度200C时的饱和渗透系数。采用土水特征曲线量测系统测试了试样的基质吸力和含水率的关系,并拟合试验数据,得出本试验试样的土水特征曲线模型。并根据土水特征模型参数拟合出试样水-汽迁移非饱和导水率和非饱和扩散系数两大重要参数与含水率的关系式。然后,采用长沙理工大学CT机对试件进行断面扫描,得出试件含水率和干密度与CT值的关系。并根据前人的大量研究,基于现有土力学理论及流体力学理论,推导得到红粘土路基水-汽迁移引起的含水率变化的数值模型。最后,基于CT试验了地下水、降雨两大影响因素下红粘土路基水-汽迁移规律,并采用水-汽迁移引起的含水率变化的数值模型计算与试验数据相互对比,验证了CT技术可无损连续性地检测研究土体水-汽迁移规律及水-汽迁移数值模型的可行性。
[Abstract]:The repair and investigation of existing road subgrade diseases show that the occurrence of roadbed diseases is related to the internal humidity of the roadbed, especially the moisture content caused by the water-vapor migration in the roadbed deviates significantly from the humidity state set when the roadbed is designed. Thus, the overall bearing capacity of the road decreases and the accumulative permanent deformation increases continuously, which leads to the road disease. It has a certain degree of influence on the study of subgrade soil-water vapor migration law. Due to the non-destructive nature of X-ray, the non-invasive nature of CT can provide clues to reveal the flow behavior and mechanism of water-steam flow in soil without disturbing the soil mass at the same time. In this paper, CT analysis technique is used to study the water vapor migration of red clay subgrade in southern China. The relationship between the matrix suction and moisture content of the sample was measured by the soil-water characteristic curve measurement system, and the model of soil-water characteristic curve of the test sample was obtained by fitting the test data. According to the parameters of soil-water characteristic model, the relationship between water vapor migration unsaturated water conductivity and unsaturated diffusion coefficient and water content is obtained. Then, the CT machine of Changsha University of Science and Technology was used to scan the section of the specimen, and the relationship between the moisture content and dry density of the specimen and the CT value was obtained. Based on the existing soil mechanics theory and fluid mechanics theory, a numerical model of water content change caused by water vapor migration of red clay roadbed is derived. Finally, based on the CT test, the water-vapor migration law of red clay roadbed is studied under the influence factors of groundwater and rainfall, and the numerical model of water content change caused by water-vapor migration is compared with the experimental data. The feasibility of nondestructive and continuous detection of water vapor migration and numerical model of water vapor migration of soil is verified by CT technique.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

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