The study delves into characterizing the mechanical parameters of the Tahar Louchene aggregate quarry unit in Ain Touta municipality, Batna province, Algeria. This investigation is crucial to address recurring instabilities commonly encountered in open-cast mines. Our approach adopts a comprehensive methodology integrating geotechnical, geomechanical, and numerical analyses, aiming to provide a thorough assessment of fractured rock mass behavior. Our methodology begins with detailed geological surveys aimed at optimal drilling site selection. Geomechanical analysis follows, focusing on fracturing and evaluating rock mass quality, complemented by geotechnical investigations featuring in-situ testing. To gather representative samples, we extracted eighteen cylindrical cores (102 mm × 204 mm) from various benches using a mechanical coring drill. These cores underwent rigorous physical characterization, geochemical analysis, and mechanical testing. Furthermore, 3D FEM numerical modeling was applied to comprehensively assess rock edge stability. The outcomes of our study unveil the presence of four distinct discontinuity sets within the primary formations, with particular emphasis on fault families of geological significance influencing deposit configuration. These fault structures provide valuable insights into stress history and tectonic evolution that directly impact the stability of the quarry. Moreover, our analysis identified various failure types, notably exacerbated by blasting practices that reduce safety factor values, highlighting the critical need for improved safety protocols. Our approach not only contributes to enhancing mining efficiency and productivity but also prioritizes the safety of equipment and personnel in open-cast mining operations across Algeria.
The characterization of phosphorite features within specific North African sedimentary series remains incomplete. Hence, the primary aim of this research is to determine the composition of powder patterns and phosphatic allochem fragments within the Jebel Dhyr syncline, situated in northeastern Algeria. By focusing on this region, the study endeavors to investigate the mineralogical properties and geochemical aspects of Paleocene-Eocene phosphorites in the broader context of North Africa. The methodology employed encompasses geological, petrographic, geochemical, and mineralogical analyses of the rocks. To achieve this objective, we have employed various techniques including thin section analysis, atomic absorption spectrometry, and X-ray diffraction (XRD). The geological section across the Jebel Dhyr area has revealed a succession of horizontally layered rocks. These rocks consist of eight prominent phosphorite layers interspersed with carbonate formations. Additionally, occasional thin layers of flint can be observed within these carbonate layers. XRD analysis of the whole rock established the presence of apatite group minerals such as hydroxylapatite, fluroapatite, francolite, and dahllite. Other minerals identified include carbonates, quartz, zeolites, feldspar, clays, sulphides, and gypsum. XRD recordings on the phosphatic allochem grains (pellets, coprolites, intraclasts, and shark teeth) identified different mineral phases, with coprolites and pellets showing hydroxylapatite and fluorapatite, sometimes associated with dahllite, while granules of different forms revealed hydroxylapatite associated with fluorapatite or francolite. Teeth from the Jebel Dhyr phosphate beam showed the systematic presence of fluorapatite. This study provides valuable information for the comprehensive utilization of phosphorus resources in the Algeria-Tunisia border.
Sinkhole (doline) collapse is one of the major natural hazards threatening people and property in the Middle East and North Africa (MENA) region, especially if the bedrock structure is epi-karstic, covered by encrusted material. Many dolines-avens collapses have been recorded in urban and rural areas in Northeast Algeria. Our study identifies localized deformation that may be caused by a sinkhole activity based on the electrical resistivity tomography (ERT) imaging in Setifian high plains. For this task, we conducted 2-D Wenner and Wenner-Schlumberger transects profiles. The geological and hydrogeological study helped to calibrate the resistivity model, and in this regard, expound on the proneness of the limestone layer to collapse. The obtained model highlights the heterogeneity of the subsurface. The inverted transects allowed the investigation of 20 m depth with Wenner array and 52 m with Wenner-Schlumberger. The Wenner inverted models imaged the chimney and different karst networks until 20 m depth; even as the Wenner-Schlumberger models imaged a new karstic cavity in the limestone layer. ERT imaging has once again proven its effectiveness in mapping sinkholes based on its ability to detect resistivity. Our research can certainly benefit karst collapse monitoring in other areas of the high plain region.
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