B. Alipenhani; A. Majdi; H. Bakhshandeh Amnieh
Abstract
Determining the hydraulic radius of the undercut in the block caving method is one of the key issues in this method. The hydraulic radius is directly related to the minimum caving span. In this research work, the rock mass cavability is investigated using the UDEC and 3DEC software. Since the factors ...
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Determining the hydraulic radius of the undercut in the block caving method is one of the key issues in this method. The hydraulic radius is directly related to the minimum caving span. In this research work, the rock mass cavability is investigated using the UDEC and 3DEC software. Since the factors affecting the cavability are very diverse and numerous, firstly, by 2D modeling in the UDEC software and examining the trend of changes in the minimum caving span, the most important factors including the depth, dip of the joint, number of joints, angle of friction of the joint surface, and joints spacing are selected for the final study. The variation trend of each variable is investigated by keeping the other variables constant (single-factor study) among various factors. In the second step, the minimum caving span for the five main factors and values is determined in the single-factor study using the SPSS software and the multivariate regression method. Then the power function of the minimum caving span is chosen based on the selected variables with a coefficient of determination of 0.76. In continuation, a simple 3D model is built from the undercut. A linear equation is achieved between the results of the 3D and 2D modeling results in similar conditions. In a model with certain conditions, using the equation obtained from the numerical method, the calculated hydraulic radius of caving is 22.5 m, which is close to the result obtained from the Laubscher's empirical method with the same condition (24 m).
M. Mohammadi Behboud; A. Ramezanzadeh; B. Tokhmechi
Abstract
Multiplicity of the effective factors in drilling reflects the complexity of the interaction between rock mass and drilling bit, which is followed by the dependence of parameters and non-linear relationships between them. Rock mass or, in other words, the formation intended for drilling, as the drilling ...
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Multiplicity of the effective factors in drilling reflects the complexity of the interaction between rock mass and drilling bit, which is followed by the dependence of parameters and non-linear relationships between them. Rock mass or, in other words, the formation intended for drilling, as the drilling environment, plays a very essential role in the drilling speed, depreciation of drilling bit, machines, and overall drilling costs. Therefore, understanding the drilling environment and the characteristics of the in-situ rock mass contributes a lot to the selection of the machines. In this work, a 1D geo-mechanical model of different studied wells is built by collecting the geological data, well logs, drilling data, core data, and pressure measurements of the formation fluid pressure in various wells. Having the drilling parameters of each part of the formation, its specific energy is calculated. The specific energy index can be used for predicting the amount of energy consumed for drilling. In order to find the relationship between the drilling specific energy (DSE) and its effective parameters, the multivariate regression model is used. Modeling DSE is done using the multivariate regression, which contains the parameters rock characteristics, well logs, and a combination of these two features. 70% and 30% of the data are, respectively, selected as the training and test for validation. After analyzing the model, the correlation coefficients obtained for the training and test data were, respectively, found to be 0.79 and 0.83. The parameters uniaxial compressive strength (UCS), internal friction angle, and fluid flow are among the most important factors found to affect DSE.
