摘要
本文利用ＣＴ对岩石、土壤、水体多种成分的冻结过程进行了实验研究。阐述了Ｘ射线与物质的相互作用，ＣＴ检查实验样品的数学原理。对图像的分辨率和伪影进行了讨论，对实验样品的最佳扫描条件进行了分析。为了定量分析岩土ＣＴ图像，以便深人地动态研究在不同实验过程中土样内部组织结构的变化，物质成份的迁移，需要针对扫描样品建立数值方程。通过对各种形状、尺寸、密度和组分的标准样品进行大量的ＣＴ扫描，对理论方程进行了验证。对扫描数据的统计分析说明，ＣＴ值随物质密度增加而线性增加，其斜率与物质成份有关；对于高密度的物质，ＣＴ值随着样品直径的减小而增加。为了以统一的数学模型描述实验样品的ＣＴ值，对理论公式进行调整、建立了半经验数值方程。利用数值方程可以定量分析岩土样品在冻结过程中的水份迁移，冻结澎胀变形；在外力作用下组织结构的变化；在温度变化过程中在冻结层面及未冻水的含量；在自然状态中材料的孔隙度等等工程科学研究中的问题。实验证明，ＣＴ用于岩土及其它材料科研中具有较高的价值。
As a system of more composition and dispersed phase,since existence ofrock and ice, the thermal and mechanical properties of frozen soil become quite compliCated.Under the certain condition,the change of internal composition and structure is basis data onstudy of frozen soil.Through transforming of technique,the medical CT is applied in test offrozen soils.Thus it is achieved for both continuous undamaged measurement and quantitativedescription of internal structure change of sample under different experimental conditions.Meanwhile,we also can obtain directly the quantitative picture of different layers.For continuously dynamic measurement,a special experdriental device matched with CT isdeveloped. Using this device,sample may be applied pressure uniaxial and triaxial stress condi conditions and can keep the temperature precision of less than ± 0. 5°in environment of 0- 30℃.Temperature and pressure may change with requirement of tests.Through scanning and mea suring of several hundreds of samples which have different shape,dry density and water con terrt, we have obtused quantitative relation among CT value,shape, dry density and watercontent. Based on this relation, we may analyse quantitatively change of sample under differ ent conditinns of test.Through a large number of scanning of Lanzhou loess,the numericaleveluation which connected soil parameter and CT data have been created.It is found that the strengthening and softening action of structure of frozen soil are con trolled by growing microcracks,being broken particle aggtegates and extending structuraldamage in creep process,as well as the form characteristics of creep process. Since actinn ofshear stress,the damage of ftozen soil firstly occurs in the centre of sample, then spread to wards outside and last results in damage of whole structure.
出处
《CT理论与应用研究（中英文）》
1994年第3期8-12,共5页
Computerized Tomography Theory and Applications
关键词
数值分析
CT
冻土
岩土实验
s: Digital Analysis,CT Frozen Soil Experiment
