Determination of Caving Hydraulic Radius of Rock Mass in Block Caving Method using Numerical Modeling and Multivariate Regression

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 ۳DEC software. Since the factors affecting the cavability are very diverse and numerous, firstly, by ۲D 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 ۰.۷۶. In continuation, a simple ۳D model is built from the undercut. A linear equation is achieved between the results of the ۳D and ۲D 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 ۲۲.۵ m, which is close to the result obtained from the Laubscher's empirical method with the same condition (۲۴ m).

Keywords:

Cavability , minimum caving span , Numerical method , Multivariate Regression