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为定量地研究节理岩体的损伤演化规律,对岩体石膏模型试件单轴压缩试验过程中拍摄的表面数字图像进行处理分析。编制Matlab程序,实现单个裂纹的识别、裂纹长度和方位角、总裂纹面积分数和总裂纹分形维数的计算。对节理倾角和节理连通率这2个参数组合变化下的试件表面裂纹图像的分析结果为:(1)试件表面总裂纹面积分数和总裂纹分形维数变化规律基本相似,在各节理连通率和各节理倾角下,2个参量都随轴向应变的增加而增大;(2)可将试件分为两大组,节理倾角为0°,15°,75°,90°试件(劈裂破坏为主)和节理倾角为30°,45°,60°的试件(剪切破坏为主),第1组试件表面的总裂纹面积分数和总裂纹分形维数值都高于第2组试件;(3)具有相同节理连通率的试件,在试验开始点不同节理倾角的总裂纹面积分数基本相同,在峰值荷载点和试验结束点的总裂纹面积分数随节理倾角的变化曲线基本呈V型(最小值在节理倾角为45°处,最大值在节理倾角为0°处);(4)表面裂纹在试验开始时和加载过程中的各向异性分布特征,可以用裂纹面积分数沿裂纹方位角的分布图来表征。研究结果表明,表面裂纹图像分析可以有效地定量研究节理岩体试件的各向异性损伤演化特征。
In order to quantitatively study the damage evolution rule of jointed rock mass, the surface digital images taken during the uniaxial compression test of the rock mass gypsum model specimen were processed and analyzed. The Matlab program is programmed to realize the calculation of single crack identification, crack length and azimuth, total crack area fraction and total crack fractal dimension. The analysis results of the surface crack images under the combination of two parameters of joint inclination and joint penetration rate are as follows: (1) The variation of the total crack surface area fraction and the total crack fractal dimension are basically similar, Rate and inclination of each joint, the two parameters increase with the increase of axial strain. (2) The specimens can be divided into two groups with joint inclination of 0 °, 15 °, 75 ° and 90 ° (Mainly splitting failure) and specimens with the inclination angle of 30 °, 45 ° and 60 ° (shear failure), the total crack surface area fraction and total crack fractal dimension of the first group of specimens are higher than (2) The specimens with the same joint connection rate have the same total crack area fraction at different joint inclination at the beginning of the test. The total crack area fraction at the peak load point and the test end point with the inclination of the joint The curve of V-shape is basically V-shape (the minimum value is at the joint inclination of 45 ° and the maximum is at the joint inclination of 0 °); (4) The anisotropy distribution of surface cracks at the beginning of the test and during the loading process can be used Crack area fraction along the crack azimuth distribution chart to characterize. The results show that the surface crack image analysis can effectively quantitatively study the anisotropic damage evolution characteristics of jointed rock specimens.