| Civil and Transportation Engineering |
|
|
|
|
| Determination of mesoscopic crack fabric for rock on plan |
| LI Xue feng, WANG Qi, WANG Xing |
1. Solid Mechanics Institute, Ningxia University, Yinchuan 750021, China;
2. School of Physics and Electrical Information, Ningxia University, Yinchuan 750021, China |
|
|
|
Abstract A novel method for determination of crack fabric in rocks was proposed by considering the density, geometry and spatial distribution of cracks. The theory expression of crack tensor redefined with normalized ideas, and the trace of redefined tensor with zero-order, second-order and fourth-order is a constant, which brings a great convenience for determining crack fabric. The amplitude parameters were defined by the second variable of fabric tensor to describe the size of anisotropy, and the direction parameters were defined by the third variable to describe the direction of anisotropy. Both the second-order form and the fourthorder form of plane fabric tensor have an equivalent description with the defined parameters which are scalars with a clear physical meaning. The verification with CT tests of coal show that the method based on the principle of stereology is suitable for quantitative determination of meso cracks in rock. The density of test line has greater effect on the average crack rate and has less impact on the crack distribution. The form of test line has a greater impact on the determination of crack distribution, so it is necessary to choose the form of test lines based on test images. The simulation with second-order tensor can describe the elliptical distribution of cracks, and the simulation with fourthorder tensor can describe the four directions distribution of the plane cracks．
|
|
Published: 28 October 2016
|
|
|
岩石细观裂隙组构的平面测定方法
考虑岩石裂隙的体密度、几何尺寸和空间分布的关系,提出裂隙组构的测定新方法.该方法采用归一化的思想定义裂隙组构张量理论表达式,新的定义使得裂隙组构的零阶、二阶,四阶张量的迹均为1,极大方便了裂隙组构的试验测定.用平面裂隙张量的第二不变量定义幅值参量来描述各向异性大小,用第三不变量定义参量描述其方向,该张量的二阶、四阶形式可以用定义的参量来等价描述,参量均为标量,物理意义清晰.煤岩的CT细观试验验证表明：采用体视法原理能够很好地用于岩石细观裂隙定量测定,测试线的密度对平均裂隙率的影响较大,对裂隙平面分布的影响较小.测试线的形式对裂隙平面分布测定的影响较大,需要根据采集的图像来选用测试线的形式.二阶模拟能够很好地模拟试验的椭圆形裂隙分布规律,四阶模拟能够描述4个方向平面裂隙的分布规律.
|
|
| ［1］ KANATANI K I. Measurement of crack distribution in a rock mass from observation of its surfaces ［J］. Soils and Foundations, 1985, 25(1): 77-83．
［2］ XU H. Theoretical and numerical modeling of anisotropic damage in rock for energy geomechanics ［D］. Atlanta: Georgia Institute of Technology, 2014．
［3］ NARA Y. Effect of anisotropy on the longterm strength of granite ［J］. Rock Mechanics and RockEngineering, 2015, 48(3): 959-969.
［4］ KACHANOV M. Continuum model of medium with cracks ［J］. Journal of the Engineering Mechanics Division, 1980, 106(5): 1039-1051．
［5］ SATAKE M. Fundamental quantities in the graphapproach to granular materials ［J］. Mechanics of Granular Materials: New Models and Constitutive Relations, 1983, 7: 919．
［6］ KANATANI K I. Stereological determination of structural anisotropy ［J］. International Journal of Engineering Science, 1984, 22(5): 531-546．
［7］ ODA M. Similarity rule of crack geometry in statistically homogeneous rock masses ［J］. Mechanics of Materials, 1984, 3(2): 119-129．
［8］ ODA M. PERMEABILITY tensor for discontinuous rock masses ［J］. Géotechnique, 1985, 35(4): 483-495．
［9］ ODA M, YAMABE T, ISHIZUKA Y, et al. Elastic stress and strain in jointed rock masses by means of crack tensor analysis ［J］. Rock Mechanics and RockEngineering, 1993, 26(2): 89-112．
［10］ ODA M, KATSUBE T, TAKEMURA T. Microcrack evolution and brittle failure of Inada granite in triaxial compression tests at 140 MPa ［J］. Journal of Geophysical Research Atmospheres, 2002, 107(10): ECV 91ECV 917．
［11］ 张青成,左建民,毛灵涛.基于体视学原理的煤岩裂隙三维表征试验研究［J］.岩石力学与工程学报,2014,33(6): 1227-1232.
ZHANG Qingcheng, ZUO Jianmin, MAO Lingtao. Experimental study of threedimensional characterization of coal fractures based on stereology ［J］ Chinese Journal of Geotechnical Engineering, 2014, 33(6): 1227-1232.
［12］ XU H, ARSON C. Mechanistic analysis of rock damage anisotropy and rotation around circular cavities ［J］. Rock Mechanics and Rock Engineering, 2015,52(5): 117．
［13］ ZHU C, ARSON C. A. thermomechanical damage model for rock stiffness during anisotropic crack opening and closure ［J］. Acta Geotechnica, 2014, 9(5): 847-867．
［14］ 李学丰,王兴,袁琪.岩石裂隙组构的定量测定［J］.岩石力学与工程学报,2015, 34(11): 17.
LI Xuefeng, WANG Xing, YUAN Qi. Quantitative determination of rock crack fabric ［J］. Chinese Journal of Geotechnical Engineering, 2015, 34(11): 17.
［15］ KAWAMOTO T, ICHIKAWA Y, KYOYA T.Deformation and fracturing behaviour of discontinuous rock mass and damage mechanics theory ［J］. International Journal for Numerical and Analytical Methods in Geomechanics, 1988, 12(1): 130． |
|
Viewed |
|
|
|
Full text
|
|
|
|
|
Abstract
|
|
|
|
|
Cited |
|
|
|
|
| |
Shared |
|
|
|
|
| |
Discussed |
|
|
|
|
