基于CT扫描的岩石细观损伤规律研究

发布时间：2018-03-30 00:27

本文选题：岩石力学　切入点：三轴压缩　出处：《太原理工大学》2015年硕士论文

【摘要】：随着工程建筑事业的迅速发展，岩石力学问题成为了国内外学者研究的热门学科。但是，岩石力学毕竟还是一门发展中的学科，并且研究的对象很复杂，因此在岩石工程中还存在着大量工程技术人员难以解决的难题。本文是基于对CT图像的分析处理，获得粉砂岩试件的一些基本性质，结合损伤力学，对粉砂岩试件的本构模型进行研究。本项目属于国家自然科学基金项目（51104105）。本文首先介绍本次试验主要用到的仪器：高精度显微CT系统、微型三轴压缩仪器、小型钻铣机床和金刚石切割机，简单的描述CT扫描系统与微型煤岩试验机的结合使用方法。利用微型煤岩试验机对三种砂岩试件进行三轴压缩破坏试验，并在宏观上观察分析不同围压下各种岩石试件的破坏结果。利用微型煤岩试验机与高精度显微CT仪器相结合的方式，获得大量压缩破坏过程中岩石试件内部变化的显微CT图像，并根据不同压缩破坏阶段的CT图像对比，分析试件内裂隙的发展情况。根据CT图像不同扫描层的平均CT数的大小，分析岩石试件的整体强度及试件破坏后的强度变化，得出初始岩石密度的不均匀性和压缩破坏过程中试件损伤破坏的不均匀性。引入了微元体的概念，通过观察扫描层中试件CT数大小的分布曲线，认为岩石试件的微元强度服从weibull分布，分析在不同压缩破坏阶段岩石试件微元强度分布的变化，在试件破坏后微元强度分布曲线会向左移动。引入了损伤变量的概念，根据CT图片分析岩石试件在压缩过程中损伤变量的变化，研究了粉砂岩试件的损伤演化规律。通过CT图像分析获得的岩石压缩中展现的特性，最终还是要建立本构模型来表达。结合损伤统计的方法，将岩石试件的压缩破坏过程分成了三个阶段，分别建立每个阶段的本构模型。对粉砂岩试件的全应力应变曲线进行比较分析，，认为峰值应力与围压存在线性关系，依此建立不同围压下的粉砂岩试件的本构模型，并对该模型进行验证。
[Abstract]:With the rapid development of engineering and construction, rock mechanics has become a hot subject for scholars at home and abroad. However, rock mechanics is still a developing subject, and the object of study is very complex. Therefore, there are still a lot of difficult problems in rock engineering which are difficult to be solved by engineers and technicians. In this paper, based on the analysis and processing of CT images, some basic properties of siltstone specimen are obtained. Combined with damage mechanics, the constitutive model of siltstone specimen is studied. This paper first introduces the main instruments used in this experiment: high precision micro CT system, micro triaxial compression instrument, small drilling and milling machine and diamond cutting machine. A simple description of the combination of CT scanning system and micro coal and rock testing machine is presented. The triaxial compression failure test of three kinds of sandstone specimens is carried out by using the micro coal and rock testing machine. The failure results of various rock specimens under different confining pressures are observed and analyzed macroscopically. The microscopic CT images of the internal changes of rock specimens during compression failure are obtained by means of the combination of micro coal and rock testing machine and high precision micro CT instrument. According to the contrast of CT images in different compression and failure stages, the development of cracks in the specimen is analyzed. According to the average CT number of different scanning layers of CT images, the overall strength of rock specimen and the change of strength after failure are analyzed. The inhomogeneity of initial rock density and the inhomogeneity of damage and failure of specimen during compression failure are obtained. The concept of microelement is introduced, and the distribution curve of CT number of specimen in scanning layer is observed. It is considered that the microelement strength distribution of rock specimen is from weibull distribution, and the variation of microelement strength distribution of rock specimen in different compression failure stage is analyzed. The microelement strength distribution curve will move to the left after the specimen failure. The concept of damage variable is introduced. According to CT images, the damage evolution law of siltstone specimen was studied by analyzing the change of damage variables during compression. The characteristics of rock compression obtained by CT image analysis were analyzed. Finally, the constitutive model should be established to express the damage statistics, and the compression failure process of rock specimen is divided into three stages. The constitutive models of each stage are established, and the total stress-strain curves of siltstone specimens are compared and analyzed. It is concluded that there is a linear relationship between peak stress and confining pressure, and a constitutive model of siltstone specimens under different confining pressures is established. The model is verified.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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