نشریه روش های تحلیلی و عددی مهندسی معدن
پیاپی 42 (بهار 1404)

One of the most critical steps in the design process of a rock structure by the limit equilibrium method is to determine the shear strength parameters. Because the prediction of these parameters is always accompanied by uncertainty. In such cases, if the range in which the actual shear strength parameters are located is obtained, the results are more reliable. Hence, in this paper, an applied technique based on probabilistic methods is developed. In the first step, by developing an innovative method for two widely used failure criteria, consist of Mohr-Coulomb and Hoek Brown, statistical samples of shear strength parameters are generated and latter, using the t distribution in which the shear strength parameters are located with confidence 95% are determined separately for the two failure criteria. The available data from the previous research are used for the case study. The results of the case study indicate that the prediction of shear strength parameters with the presented method is more accurate than the conventional methods.

Quantitative interpretation of electrical resistivity tomography (ERT) and electromagnetic in low induction number (EM-LIN) data sets is possible through inversion. Data inversion of the two methods is confronted with two problems of non-uniqueness and instability, which must be solved by the use of constraints and a priori information. The more important issue is that the implementation of one geophysical method does not lead to a favorable interpretation of the subsurface structure in many cases, so the combination of geophysical data is inevitable. In this paper, the joint interpretation of resistivity and electromagnetic data in low induction number data is used for a site in South Africa. In this area, the identification of dolerite dyke is the most important goal in the exploration of underground water. Here, a 2D forward modeling code for EM-LIN and ERT is developed based on the integral equation (IE) method. Also, a linear relation between model parameters and apparent conductivity values is proposed. To invert both data sets, the weighted minimum length solution algorithm is used, and the depth weighting function is used as the model weighting matrix. The inversion of electromagnetic in low induction number indicates a relatively thick dyke in the depth range of less than 5 to 15 m and with a horizontal extension of 185 to 200 m (thickness is about 15 m). Electrical resistivity tomography recovers a two layered medium, and in the conductive layer close to the surface of the dyke, a resistive dyke is extended to near the surface. The electromagnetic method reconstructs the dyke better, while electrical resistivity tomography can recover the layered structure.

In this paper, by preparing a film with a digital camera from the surface of a flotation cell in the Miduk copper mine in Kerman province, the relationship of the mean color components of existing film frames, Haralick textural features including entropy, image uniformity and energy, as well as the texture complexity feature in three color spaces RGB, YCbCr and HSI with the mineral grade is analyzed.

This study was carried out in the eastern area of the Lut block and sheets of Basiran and Kodegan. Due to the existence of numerous vein copper deposits in this area, the possibility of porphyry copper mineralization was evaluated by using the zonality indicators related to porphyry copper deposits and the singularity method, and tectonic and geological maps. In this research, after modifying the censored data, the histogram of the abundance of elements related to the used zonality index, including copper, lead, zinc, and molybdenum, was drawn, and after software processing of the data using logarithmic images of grade-area, the amount of anomalous grade and background. is identified. The dispersion map of lead, zinc, and copper elements was prepared and analyzed, and the dispersion elements were used as one of the weighting layers in the hierarchical integration method of AHP. Also, the distribution map of the index of supra-mineral and sub-mineral zonality was prepared, and by combining the two maps, the layer of areas rich in lead, zinc, copper, and molybdenum was obtained and used in the AHP method. The singularity method related to the surface production of the zonality index in windows with an area of 2,500 square meters was used to prepare one of the weighting layers in the hierarchical method. In the geological map of the region, the Oligo-Miocene intrusive masses were integrated as a suitable substrate for hosting copper deposits with the tectonic evidence layer and were used as one of the main weighting parameters in the AHP method. The use of the geological layer in the AHP matrix led to the removal of alluvial areas or Quaternary sediments in the detection of promising porphyry copper mineralization areas. The desired layers were combined with each other in the GIS software environment by the AHP add-on, and a favorable potential map for porphyry copper mineralization was prepared. In the final result of hierarchical integration, the area of 490 square kilometers out of 5200 square kilometers of the investigated area was introduced as a promising area. In this research, using quantitative variables, a qualitative and functional map was prepared to advance the preliminary explorations of the region. In order to validate the processing, 22 known mineral indices related to copper mineralization were used, of which 17 indices, equivalent to 77% of them, were found in the areas identified in this study.

This paper investigates the effect of geotechnical parameters on the prediction of building damage severity due to tunneling-induced settlement. The influence of soil elastic modulus, cohesion, and internal friction angle on ground displacement and building deformation was studied using the numerical finite element method in the Tehran Metro Line 7 tunnel project. The severity of the building damage was analyzed based on an assessment of building deformation parameters. The results indicate that building damage severity is significantly sensitive to changes in soil elastic modulus. Minor changes in elastic modulus can lead to a shift in damage severity from structural and severe (damage grades 4 and 5) to non-structural and minor (damage grades 0 and 1). In contrast, changes in internal friction angle do not have a significant impact on damage severity. However, an increase in cohesion can be somewhat effective in reducing damage severity.

This research adapts the ground reaction curve (GRC) method, traditionally used in tunnel engineering, to analyze wellbore stability and determine the optimal drilling fluid weight in oil and gas operations. The objectives are to assess wellbore stability under varying conditions and establish a safe drilling fluid pressure window. The methodology employs analytical solutions based on the Mohr-Coulomb failure criterion and numerical modeling using FLAC software. Results demonstrate that parameters such as pore pressure, in-situ stress ratios, and wellbore radius influence wellbore convergence, with the numerical GRC method providing a larger safe drilling fluid pressure window compared to the analytical approach, potentially enhancing drilling efficiency and reducing operational risks.nalytical methods improves stability assessment. An exception occurs in specific hydrostatic cases where the numerical window narrows slightly, possibly due to differing criteria emphasis. Theoretically, this approach refines wellbore mechanics understanding; practically, it suggests cost and risk reductions. Validation with field data remains necessary. The study concludes that the GRC method is a promising tool for optimizing drilling fluid design, recommending further testing across diverse formations.