Original Research Paper
Blessing Olamide Taiwo; Gebretsadik Angesom; Yewuhalashet Fissha; Yemane Kide; Enming Li; Kiross Haile; Oluwaseun Augustine Oni
Abstract
Rock blast production rate (BPR) is one of the most crucial factors in the evaluation of mine project's performance. In order to improve the production of a limestone mine, the blast design parameters and image analysis results are used in this work to evaluate the BPR. Additionally, the effect of rock ...
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Rock blast production rate (BPR) is one of the most crucial factors in the evaluation of mine project's performance. In order to improve the production of a limestone mine, the blast design parameters and image analysis results are used in this work to evaluate the BPR. Additionally, the effect of rock strength on BPR is determined using the blast result collected. In order to model BPR prediction using artificial neural networks (ANNs) and multivariate prediction techniques, a total of 219 datasets with 8 blasting influential parameters from limestone mine blasting in India are collected. To obtain a high-accuracy model, a new training process called the permutation important-based Bayesian (PI-BANN) training approach is proposed in this work. The developed models are validated with new 20 blast rounds, and evaluated with two model performance indices. The validation result shows that the two model results agree well with the BPR practical records. Additionally, compared to the MVR model, the proposed PI-BANN model in this work provides a more accurate result. Based on the controllable parameters, the two models can be used to predict BPR in a variety of rock excavation techniques. The study result reveals that rock strength variation affects both the blast outcome (BPR) and the quantity of explosives used in each blast round.
Original Research Paper
Farouk Sayed; Mohamed Saleh Hassan Hammed; Ahmed Gaber Shided; Ahmed Wagih Hussein
Abstract
The northwestern margin of the Red Sea is developed as several rift-related fault blocks. These fault blocks comprise two mega tectono-stratigrahicsuccessions; the Pre-riftsuccessioncould be sub-divided intothe Precambrian Basement rocks and theUpperCretaceous-Lower Eocenedeposits,whilst the Syn-rift ...
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The northwestern margin of the Red Sea is developed as several rift-related fault blocks. These fault blocks comprise two mega tectono-stratigrahicsuccessions; the Pre-riftsuccessioncould be sub-divided intothe Precambrian Basement rocks and theUpperCretaceous-Lower Eocenedeposits,whilst the Syn-rift sequence includesthe Oligocene to Quaternary deposits. Lithologic differentiation of these rock units being encountered in thestudied area is accomplishedutilizing different remote sensing imagery enhancement techniques of the OLI data (Landsat-8) aided with field verification. Spectral signature analysis of different rock units, false-color composite, band-ratio, principle component analysis, minimum noise fraction, and independent component analysis are powerful tools in discrimination of the main rock units.The maximum likelihood distance supervised classificationtechnique is a robust tool in the identification of the contact between the different rock units. Radiometrically terrain corrected (RTC) DEM data extracted from PALSAR with a spatial resolution of 12.5m is utilized for the construction of a 3D perspective view image of the studied area. The present study offers a unique method for lithologic discrimination of main rock unitsutilizing OLI images, and introduces an enhanced high-resolution structural map of the studied area aided with field verification.
Original Research Paper
Bijan Afrasiabian; Kaveh Ahangari; Ali Noorzad
Abstract
High-level vibrations caused by blasting operations in open-pit mining can exert adverse effects such as destruction of surrounding surface structures. Therefore, it is essential to identify the factors effective in mitigating the damaging effects of ground vibration in open-pit mines, and monitor them. ...
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High-level vibrations caused by blasting operations in open-pit mining can exert adverse effects such as destruction of surrounding surface structures. Therefore, it is essential to identify the factors effective in mitigating the damaging effects of ground vibration in open-pit mines, and monitor them. This study investigates the effects of some of the most important blast design parameters in a row of blast holes. According to the advantages of numerical methods, the 3D discrete element method is employed for this purpose. The Peak Particle Velocity (PPV) values are measured along the central hole at the distances of one meter. The results obtained demonstrate that an increase in the blast damage factor and inter-hole delay time results in higher PPV values. However, the increased delay time has no remarkable effect on reducing the development of the blast damage zone. On the other hand, as the decoupling increases, the PPV values diminish, leading to substantial reductions in the ground vibration and rock mass damage. It is also observed that the elimination of sub-drilling does not significantly reduce ground vibrations. The analysis of the results obtained from the numerical modeling show that the discontinuities of the rock mass act as a filter, which could decrease the wave energy by more than 90%. Moreover, it is found that the direction of the discontinuities also affects the emission of waves caused by the blast. The PPV values are reduced, and the damaged zone is less developed if the discontinuities are opposite of the slope surface.
Case Study
Hasan Alizadeh; Mahnaz Nedaei; Negar Tirandaz
Abstract
One of the significant negative factors involved in exploiting granite stones as ornamental stones is the presence of heterogeneous fractures within the rock mass. Joints can either be destructive or beneficial in the production granite piles and building stone mines depending on their characteristics. ...
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One of the significant negative factors involved in exploiting granite stones as ornamental stones is the presence of heterogeneous fractures within the rock mass. Joints can either be destructive or beneficial in the production granite piles and building stone mines depending on their characteristics. This work focuses on evaluating the joints in the Divchal mine area of Kelardasht, north Iran. To get to that point, the main faults are surveyed from the aerial photograph, geological and tectonic maps, and field observations. According to this implementation, a density map of faults is provided for the entire studied area. The characteristics of the main joints including the length, slope, number, and orientation are collected in the mine area. The volumetric percentage of joints ( ) and joint set spacing ( ) parameters are computed at specific stations to identify suitable locations for granite extraction. The findings of this work suggest that the lower the value of ( < 10), the larger the blocks can be extracted. On the other hand, at the high values, the width of the extraction block increases. These conditions are typically found in locations far from the main faults where the density of joints is low, and as a result, the distance between joints is higher. The values > 60 indicate a crushed rock mass, and are typically observed in clay-free shear zones. It is recommended that the opening of the working face be avoided in situations near the main faults due to the fragmentation of rocks and denser joint spacing.
Original Research Paper
vahab sarfarazi; Mohammad Omidi manesh; nima babanouri; amir rezaei
Abstract
This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile ...
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This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile strength of cement sheath is 1.2 MPa. The cement sheath model is calibrated by outputs of the experimental test. Secondly, the numerical HCCD model and CSTBD model with diameter of 100 mm are prepared. The notch lengths are 10 mm, 20 mm, 30 mm, and 40 mm. The tests are performed by the loading rate of 0.018 mm/s. When the notch length in CSTBD is 40 mm, the external work is decreased 48%, related to the maximum external work of model with notch length of 10 mm (0.225 KN*mm decreased to 0.116 KN*mm). When the notch length in HCCD is 30 mm, the external work is decreased 33%, related to the maximum external work of model with notch length of 10 mm (0.06 KN*mm decreased to 0.04 KN*mm). The fracture energy is largely related to the joint length. The fracture energy is decreased by increasing the notch length. In constant to the notch length, the fracture energy of the CSTBD model is more than the HCCD model. Mode I fracture toughness is constant by increasing the notch length. The HCCD test and the CSTBD test yield a similar fracture toughness due to a similar tensile stress distribution on failure surface. The experimental outputs are in accordance to the numerical results.
Original Research Paper
Ali Nouri Qarahasanlou; Alireza Dolatshahi
Abstract
Engineers use various methods to evaluate the performance of concrete structures under dynamic loads, including numerical simulations, laboratory experiments, and field tests. By combining the results of these methods, the engineers can develop a comprehensive understanding of the behavior of concrete ...
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Engineers use various methods to evaluate the performance of concrete structures under dynamic loads, including numerical simulations, laboratory experiments, and field tests. By combining the results of these methods, the engineers can develop a comprehensive understanding of the behavior of concrete structures under dynamic loads and use this information to design more resilient structures capable of withstanding these loads. In this work, four models of the concrete lining of the circular tunnel are simulated to investigate the effect of the pre-cracked in the tunnel's concrete lining under an internal explosion loading. A crack in three different locations at angles of 0, 45, and 90 on the horizontal axis of the tunnel is investigated and analyzed. The coupled Eulerian-Lagrangian method and the constitutive behavior, such as concrete damage plasticity for concrete and Drucker-Prager for soil, allows a more accurate simulation of the internal explosion loading scenario. The selection of Trinitrotoluene and the Jones-Wilkins-Lee equation of state for the explosive provides a realistic representation of the behavior of the explosive material. The modeling results show that in an internal explosion, by examining three different locations of a crack in the concrete, the occurrence of a crack in the crown of the tunnel is more critical than two crack locations. Hence, the existence of a crack with a length of 100 cm and a depth of 15 cm in the crown of the tunnel increases the tensile damage zone by 16.59% compared to the case where there is no crack.
Original Research Paper
Mohammad Rezaei; Milad Ghasemi
Abstract
Resource estimation and determining the grade distribution is one of the most important stages in planning and designing the open-pit and underground mines. In this work, a new mythology is used for resource estimation of the Angouran underground mine based on the optimized integration of the indicator ...
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Resource estimation and determining the grade distribution is one of the most important stages in planning and designing the open-pit and underground mines. In this work, a new mythology is used for resource estimation of the Angouran underground mine based on the optimized integration of the indicator kriging (IK), simple kriging (SK), and inverse distance weighted (IDW) methods. For this purpose, waste blocks are first removed from the block model using the IK method. Then the amount of mineral resource is estimated using the SK and IDW methods. Indeed, variograms are developed to estimate the grade of zinc minerals in the three used methods. Variograms analysis in three directions prove that the studied resource is anisotropic. Also the validation results confirm that the correlation coefficients between the measured and estimated zinc values by the SK and IDW methods equal to 0.76 and 0.75, respectively. Knowing this satisfactory result, a 3D model of the resource is prepared using the IK method, in which the ore and waste sections of the Angouran underground mine are separated definitely. According to the above methodology, the calculated resource of the Angouran underground mine using the SK method is achieved 1373962.5 tons with an average grade of 30.11%, whereas the estimated amount of this resource is attained 1349325 tons with an average grade of 31.88% using the IDW approach. The verification results show that the suggested methodology based on the optimized integration of the IK, SK, and IDW methods can be successfully applied for resource modeling and grade estimating of the Angouran underground mine.
