土石混合体变形破坏结构效应的CT试验研究

STRUCTURE EFFECT STUDY OF DEFORMATION AND FAILURE OF ROCK AND SOIL AGGREGATE WITH CT TECHNIQUE

利用计算机X射线断层扫描技术,实时监测单轴加载作用下土石混合体试样内部结构的变化规律,分析土石混合体变形破坏的结构效应。基于CT的定位扫描原理,研究试样内部块石的运移规律,并建立内部结构变形与宏观变形的联系。研究结果表明:土石混合体宏观变形破坏主要受控于其内部块石位置的不断调整;等效结构变形量能很好地表征土石混合体的结构性变形。采用阈值分割处理方法分析CT图像,获得加载过程中试样的内部剖面图,并对试样变形破坏的结构效应进行分析。结果表明:试样内部损伤和裂纹扩展起始于块石周边应力集中区,沿块石与土的接触面扩展,直至形成贯通破裂面。通过采用CT技术对土石混合体变形破坏过程进行分级加载实时扫描的研究,为此类介质边坡工程的监测预警提供理论基础。

In order to study the structure effects,interior structural deformation of rock and soil aggregate(RSA) under uniaxial compression is studied through the X-ray computed tomography(CT) real-time scanning tests. Based on the scan orientation principle of CT,movement of rock fragments in RSA is analyzed. Moreover,the relationship between interior structural deformation and macroscopic deformation of RSA is studied. The results show that macroscopic deformation and failure of RSA are mainly caused by the position adjustment of interior rock fragments. It is also shown that the integral deformation of rock fragments in RSA can be represented by equivalent structure deformation. By using the method of image threshold segmentation,profiles of the sample are obtained and analyzed. The profiles indicate that interior damage and cracks of sample initiate from the contact zone between rock fragments and soil,and then extend around rock fragments,until they form fracture planes. The results can provide theoretical basis for the monitoring and warning of RSA slope.