Résumé: The size of rock fragmentation plays an important role in the economic efficiency of surface mining operations. It directly affects the costs associated with drilling, blasting, loading, and crushing. This study aims to explore the influence of blast design factors such as blast hole length, stemming length (SL), and powder factor on rock fragmentation in a limestone quarry. Digital Image Analysis (DIA) was employed to determine the mean fragment sizes (MFS-X50) and maximum fragment size (MaxFS-X80) of the rock. Following each blast, several images of the entire muck pile were captured during the loading stages and subjected to fragmentation analysis using WipFrag software. The results obtained reveal that the optimal rock fragment size (MFS-X50, and MaxFS-X80) of rocks depends strongly on both blast design parameters and explosive factors.

Résumé: Abstract. In quarries and mines, the drilling and the blasting activities is an essentially fundamental way of excavating rock. The blasting process is an integral and important part of mining operations and is intrinsically destructive for a variety of different reasons, notably efficiency, cost effectiveness and the capacity to shatter away even the most solid rock. The primary and main purpose of designing a blast pattern in an open pit or quarry is to use quantities of explosives to fragment the rock material down to smaller pieces and shapes that can make it easier to carry out various subsequent operations such as excavation, charging, transporting, crushing, grinding etc. The conception of a blasting model depends on two sorts of variables: firstly uncontrollable factors, such as the geological structure and the properties of the rock mass. Secondly controllable factors, such as the geometric model (height of the bench, length of the charge, diameter, spacing, burden, stemming length, etc.), the properties of the explosives used (type, resistance, energy, etc.) and the temporal parameters (time delay and initiation sequences). The different fragmentation blasting analysis procedures have inherent difficulties, which result in varying levels of accuracy. Consequently, each technique is adapted to a particular purpose. This research assessed and then compared the particle size distribution of limestone rocks from the New Cement Quarry (NCQ) at Setif -NE Algeria, using the Wip Frag computer imagery processing program and one of the empirical models called Kuz-Ram. Three blasts from the quarry, using different mesh designs in terms of load and spacing (rectangular, square and triangular) analyzed using the two methods. The design parameters of the blast obtained and evaluated as input to the Kuz-Ram model. Pictures of the pile taken and downloaded to the Wip Frag software for analysis. The obtained results in the case of a change in the geometrical parameters of the explosion show that a significant reduction in the size of the oversized products observed by the numerical method. Furthermore, in this study, the ratio between the spacing and the charge in the case of the triangular pattern has a major influence on the size of the fragments and makes it possible to make optimum use of the distribution principle and the amount of energy of the explosive.

Résumé: The objective of our work is the study of the influence of the dynamic load due to the use of the explosive in the stability of the slope of an open pit mine, for this purpose we used the method of limit equilibrium to calculate the value of the safety factor through the geotechnical software SLIDE. On the one hand the calculation was carried out under static loading and on the other hand the dynamic loading is taken into account, which allowed us to conclude that the dynamic load influences the safety coefficient. Finally, a proposal to stabilize the slope at through a reprofiling of the bench is presented.

Résumé: The results of analyses performed and aimed to the investigation of the stability of a rock slope in open pit mine in Tebessa (East Algeria). Processes of sliding, toppling and rolling of large blocks, affect this slope. Sloped bench faces that compose the overall slope in the studied case in this paper are evaluated from the stability prospective by applying a variety of stability analysis methods. The adopted approach is based on laboratory tests on understudied samples to designate the mechanical parameters and numerical modeling by implementing the finite element method. The latter, a vital tool to the quantitative determination of deformation mechanisms in large slope instabilities, is used to unravel the uncertainty of mechanical homogeneity properties of the involved materials at the level of discrete meshes in numerical computations that type of application proposes a procedural combination of an assortment of calculation stability methods through three steps. The first step is to determine the mechanical parameters of Kef-Essnoun rock mass by using slope mass rating (SMR) classification scheme, developed by Romana, to depict the strength of an individual rock slope. This system is based on the rock mass rating (RMR) geo-mechanical classification system of rocks, developed by Bieniawski, who refurbished that system with quantitative guidelines to get the rate of influence of adverse joint orientations. The second step is to uses the abacus method to estimate the stability of open-pit mines. The last step is to use a numerical modeling by applying Plaxis 8.2 calculation code. The analyses indicate that the slip problem is the presence of fragile phosphate-marl interfaces at the base of the phosphate layer.

Résumé: Although researchers have realized varying degrees of success in small-scale physical in situtesting of rock blasting, most will agree that the greatest uncertainty stems from the uncontrollable field variables. Given the diverse nature of field conditions encountered, there exists no reliable and proven method of predicting fragmentation. Due to the lack of adequate field controls, it is unlikely that a universal physical model will ever be developed for all blasting. This paper presents the results of a test conducted at the Hadjar Essoud quarry to investigate the problems associated with discontinuities in the rock, which are among the factors causing the reduction of the resistance of the rocks to the explosives. Nevertheless, the distance between the joints, their dip and strike, and the position of the detonator play a significant role in the final fragmentation of the rock. In this work, we studied the role of the abovementioned factors on models of limestone rock of 150 × 375 × 450 mm. Accurate measurement of blast, fragmentation is important in mining and quarrying operations, in monitoring blasts, and optimizing their design. We shall use the Kuznetsov–Rammler method to measure fragmentation. It shows great potential as a practical aid to predict and control the quality of the fragmented material in the Hadjar Essoud quarry.