| With the rapid development of science and technology, the situation of global economic integration gradually formed, each country’s economy has increased by leaps and bounds, in order to meet the people of production resources and make full use of all kinds of energy, people constantly develop the upper top space; At the same time excavation of underground space development and gradually advancing to the deep. Rock creep characteristics refers to the constant stress under the action of continuously, with the increasing of time, the process of rock mass deformation continues to grow. Due to the natural attribute of rock are extremely complex, the traditional description methods exist a certain degree of limitation. Therefore, the application of fractal geometry in the study of rock mechanics, for solving the problem of engineering practice has important application value, and for the development of the theory of rock mechanics has very important significance.Mechanics laboratory in this paper, application of shandong agricultural university changchun branch new test instrument co., LTD, introduced in the production of SAW- 2000 microcomputer control electro-hydraulic servo rock testing machine, argillaceous sandstone specimen of kongzhuang mine creep test, the creep test curve is obtained, the rock fracture and its macro images. XPV- 900 E through reflective polarizing microscope to observe argillaceous sandstone fracture information. The software ImageJ application by polarized light microscopy to obtain macroscopic pictures and microscopic image processing to grayscale. Application Toolbar Analyze the Fractal box count tool for processing, using ImageJ software under the box counting method to calculate the fracture Fractal dimension values.Through the analysis in this paper, combined with the result of creep test data, the application of Matlab software on the creep test curves better model fitting and creep property law, the creep equation is determined. With the increase of test stress level, and creep function fitting parameter E0 increasing, instructions for shaly sands, with the increase of stress and strain of sandstone also increases accordingly, Correlation coefficient Correlation coefficient σ0 and creep parameters E after fitting slightly lower than σ0 and creep after fitting parameters E0,and creep function fitting parameters can be seen that with the increase of test stress, fitting parameters E increases, when the stress increases to 20 MPa, fitting parameters E basic stable, E no longer changes with the change of the stress. Higher correlation coefficient σ0 and creep after fitting parameter ?,Stress σ0 and creep parameters ? exist obvious linear relationship, the corresponding limit stress of specimen creep curves of creep curve appeared on the stage of creep rate has increased dramatically, creep fitting parameters can v can well reflect the extent of creep curve upward, become warped on creep curve, the greater the amplitude parameter v is smaller, the curve slightly upward, destroyed immediately.Passed the test for rock specimens, macroscopic and mesoscopic picture information using ImageJ software calculated fractal dimension, the study found that the rock specimen macro image fractal dimension value and the limit of argillaceous sandstone specimen strength there is no obvious linear relationship, but with the increase of rock ultimate strength gradually, the rock fracture fractal dimension value also continue to increase. Also shows that rock specimen under the vertical load, with the increase of strength, specimen creep process is more complicated.In mesoscopic scale, argillaceous sandstone the magnification of the fractal dimension values are very close, generally between 1 and 2, show that macro mesoscopic scales, different magnification, rock fracture is statistical self similarity. Argillaceous sandstone rock ultimate strength in size and the size of the fractal dimension value of the four magnification there is no obvious linear relationship, but as the rock’s ultimate strength increase of fractal dimension is increasing, after the destruction of structural plane is becoming more and more complex, it has to do with this paper get the argillaceous sandstone damage when the macro picture with the size of the ultimate strength of rock specimen fracture the relationship between the fractal dimension value size is almost the same. |
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