| Rock mass consists of rock blocks and discontinuity structural plane, and the latter decides on the strength and destruction of the rock. Therefore, a scientific and reasonable analysis on shear strength of the structural plane of the rock is the key to the evaluation of the integrality and stability of rock mass. Based on field measurement and experimental data, this paper studies the granitic mass in the pre-selected site in Beishan area, Gansu province, and makes an interval probability analysis on the shear strength of the structural plane of the rock in Jijicao field in Beishan area, Gansu province. The study content and results are listed below:(1) According to the box-counting method of the fractal theory, each testing zone in Beishan area is divided in homogeneity by grouping-fractal dimension method using self-compiled program. In this method, the objects are grouped by occurrence. A preliminary division of the testing zones is made according to joint attitude factors. Then, a further division of homogeneity, which can help draw a conclusion that is more reasonable and corresponding to actual geological conditions, is made by fractal theory according to joint density and trace length. The key feature of the method is taking the effects of three important factors——joint occurrence, density and trace length into consideration at the same time.(2) Using the approach of digital close-range photogrammetry and precision control point coordinate system, and according to the advanced 3D reconstruction technique,3D models of typical homogeneous structural plane are achieved. Getting the different position of structural plane roughness curve by self-compiled MATLAB program. Roughness curve obtained by this method is much higher than the general mechanical methods in accuracy. Using the method of fractal dimension to calculate the fractal dimension value of roughness curve. Through the quantitative relation between the existing fractal dimension and roughness coefficient to determine the roughness coefficient values, and a probability distribution histogram of four groups of the structural plane roughness coefficient of typical homogeneous is drawn.(3) Based on Barton’s JRC-JCS model, the shear strength parameter of four groups of the structural plane roughness coefficient of typical homogeneous is calculated according to the field measurement of the typical homogeneous field in Beishan area, Gansu province and the experimental results. The interval probability model of the shear strength of the rock joint surface is built by Netica software according to Bayesian Network theory. The specific interval probability distribution results of friction angle and shear strength of typical homogeneous four groups of the structural plane is obtained. |
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