Résumé: Mining blasting efficiency is essential for mining operations for economic and technical reasons. Rock blasting operations should be conducted optimally to obtain a particle size distribution that optimises downstream operations, such as loading, transport, crushing, and grinding. The nature of the stemming material significantly impacts the degree of rock fragmentation during mining operations. Stemming refers to the material used to fill the space above explosives in a borehole, which helps confine the explosive energy and optimise rock fragmentation during detonation. This study aims to evaluate the stemming materials and their effect on the particle size distribution of blasted rocks at the Chouf Amar quarry in M'Sila, Algeria. The analyses performed in this study indicate that the blasting results obtained by the company reflect poor fragmentation quality, with a significant quantity of oversized fragments, making up 20–23% of the total pieces. To address this issue, a new operational blasting plan is proposed to enhance fragmentation quality. This plan employed three stemming materials: drill cuttings, 3/8 crushed aggregates, and sand. The test blasts were performed in a limestone quarry, and the results were evaluated using the highly reliable and widely respected image analysis software WipFrag 3.3. The results reveal that using crushed aggregates as stemming material significantly improves fragmentation quality, reducing the proportion of oversized fragments from an average of 23% (with sand stemming) to 2.6%.

Résumé: Purpose. The objective of the study consists in obtaining better quality rock fragmentation by using inclined holes to ensure good energy distribution and better stability of the upper wall.The Kuz-Ram model and the Langefors method are best suited to achieve the goal. Methodology. The study compares the blasting plan adopted by the Boukhadra mine located in the Wilaya of Tebessa, with that calculated by the Langefors method while using inclined holes. We chose the Kuz-Ram model as a simulation model and validation for the following reasons. Findings. The application of the proposed method of Langefors gave a satisfactory result in terms of process efficiency, the Kuz-Ram model predicts a significant reduction in the rate of oversized blocks using an inclined hole drilling technique, from 13.1 to 5.3 %. This approach appears to improve the degree of fragmentation, reduce the percentage of oversized blocks and decrease energy loss during blasting. Originality. Rock fragmentation, which corresponds to the size distribution of fragments of the blasted rock, is one of the most important indices for estimating the effectiveness of blasting works where the size of the fragments of the blasted pile plays an important role in efficient transportation, crushing and grinding.The size of the fragments depends on the characteristics of the rock mass, the type of explosive used, and the drilling and blasting pattern. Practical value. The use of inclined holes is an important technique to optimize rock fragmentation in open pit mines. The inclination can be adjusted to improve the direction and distribution of blast energy, which contributes to more efficient and uniform fragmentation of extracted rocks.

Résumé: Purpose. This paper highlights the importance of taking into account the evaluation of the strength properties of limestone rock in the Ben Azzouz quarry. The purpose is to achieve optimum blasting quality based on the information on petro-physical and mechanical characteristics of the rock. Methodology. Models have been developed to estimate physico-mechanical properties of limestone rock. The models are based on the results of many laboratory tests by petro-physical and mechanical methods. Statistical analysis was performed on simple and multiple regression equations. Findings. Linear regression models have a higher estimated success rate, as expected. The best model for estimating the compressive strength of the rock (UCS, Uniaxial Compression Strength) based on simple regression is the model containing P-Velocity as an independent variable with a coefficient of determination R2 of 0.81 and P-value = 0.000000003. Originality. To benefit from the enormous reserves in the quarry of Ben Azouz, knowing that there is no evaluation of the physico-mechanical characteristics of the rock, a set of the tests in the rock mechanics laboratory of polytechnic faculty of Mons in Belgium was carried out and limestone rock strength was estimated. Practical value. to Solid understanding of the physical and mechanical characteristics of the rock mass and the mechanism of blasting the rock is an essential step that must be taken gradually according to the development of mining works with the aim of minimizing the disadvantages in blasting and obtaining an optimal effectiveness.

Résumé: MR system and numerical modeling for mining underground excavation design of the Djebel El Ouahch tunnel, in Constantine (Algeria). The geological and geotechnical character-ization of the rock mass is important for the design of underground mining excavations. In this article, we present the results of the RMR characterization of the rock mass and the numerical modeling by the finite element method (FEM), under the conditions of the Djebel El Ouahch tunnel, Constantine (Algeria). The RMR system is a useful tool for characterization of the rock mass quality and establishing the appropriate support system. For poor rock (Class IV), the excavation should be top heading and bench 1.0 m–1.5 m advance in top heading. Support should be installed concurrently with excavation, 10 m from face. Rock bolting should be systematic with 4 m–5 m long, spaced 1.5 m–1.5 m in the crown and walls with wire mesh, Shotcrete of 100 m-150 mm in the crown and 100 mm in sides. The steel sets should be light to medium ribs spaced 1.5 m only when required. The rock mass consists of generally poor rocks with average stand-up time of 10 hours for 2.5 m span with mass cohesion ranges between 100 kPa–200 kPa and rock mass friction angle ranges from 15 to 35. The FEM project due to its precision calculates the safety factor and evaluates the principal deformations and displacements of the rocks mass. The originality of this work lies in the use of two different approaches, the RMR system and numerical method (FEM) for analyzing the quality and evaluation of the …