Wyniki wyszukiwania - BazTech

1

A mathematical approach to calculating slope stability under physical triggering forces. Application to landscape mechanics

Khaber Larbi, Zighmi Karim, Hadji Riheb

Geomatics, Landmanagement and Landscape

|

2023

|

no. 4

97--112

EN

In the field of land management, the limit equilibrium calculation method is a mathematical method that harmonizes the complex interplay of diverse factors determining the slope stability. Rooted in mechanical and mathematical principles, this method has paramount significance for guiding the course of safe land management in mountainous regions, especially in the case of infrastructure development projects. Conventional limit equilibrium techniques, while providing preliminary stability assessments, often neglect key factors that can trigger slope failure. These approaches traditionally ignore the spatial variations in soil properties, the temporal dynamics of phenomena, the kinetic responses to external loads, the complexities of geological formations, and the influences of the hydrological and climatic conditions on slope stability. Our innovative method adopts an enriched mathematical framework that redefines the landscape of force equilibrium techniques. We meticulously tailor this framework by adapting the foundational relationships derived from the Mohr-Coulomb shear strength criterion to accommodate the spatially variable geomechanical parameters. This adaptation allows us to capture the nuanced shifts in mechanical properties over the extent of the slope. Furthermore, we introduce supplementary equations that seamlessly integrate the influences of traffic-induced loads and hydraulic pressures, while also statistically quantifying the contributions of stabilizing structures. To determine the efficacy of this geomatic and landscape-centric numerical tool, we have subjected it to rigorous testing on a test slope. The outcomes derived from our mathematical model reveal the primacy of traffic-related forces as the main destabilizing agents, contrasted with the strengthening effects of reinforcements in maintaining slope stability.

2

Mining operations and geotechnical issues in deep hard rock mining – case of Boukhadra iron mine

Benyoucef Ali Ahmed, Gadri Larbi, Hadji Riheb, Mebrouk Faouzi, Harkati Elhaddi

Geomatics, Landmanagement and Landscape

|

2022

|

no. 4

27--46

EN

Underground mining operations are a very problematic task, especially in poor geotechnical conditions. The right choice of excavation and support techniques leads to adequate and secure mining operations. This should ensure the overall stability of the underground mine with the best productivity and stability performance. In this paper, an empirical model for obtaining support systems for underground galleries was applied. Then, a numerical model for the evaluation of the performance of support measures for rock masses in the Boukhadra iron mine was introduced. Extensive field and laboratory tests were performed to obtain geological, geotechnical, and mechanical data on the entire geologic formations of the (1105 m) level. The performance of the design is supported by the selection of a common support plan between RMR, Q, and UBC systems for each geotechnical unit. Therefore, the rock masses classification based on the geo-mechanical model has determined the suitable support systems. The finite element model (FEM) was used for the analysis of rock mass behaviour, displacements, stress, and plastic point distribution. The results permit the optimization of the plastic zone thickness around the gallery. The outcomes of this study could improve the stability of the mine by choosing the right direction of excavation in consideration to the direction of the discontinuity planes. In order to choose between the current and the recommended mining operations, an equivalent calculation sequence was verified. Our study demonstrated that the consideration of discontinuity sets in the orientation of excavation highly improves the mining conditions with or without support.

3

Karstic landscape detection using electrical resistivity tomography in northeast Algerian

Brahmi Serhane, Hadji Riheb, Chemseddine Fehdi, Brahmi Smail, Hamad Amor, Hamed Younes

Geomatics, Landmanagement and Landscape

|

2022

|

no. 3

103--115

EN

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.

4

Geomatics-based assessment of the neotectonic landscape evolution along the tebessa-morsott-youkous collapsed basin, Algeria

Taib Hassan, Benabbas Chaouki, Khiari Abdelkader, Hadji Riheb, Haythem Dinar

Geomatics, Landmanagement and Landscape

|

2022

|

no. 3

131--146

EN

The neo-tectonic research is interested in the study of the movements of Earth’s crust in recent geological times. It could explain the deformation mechanisms that lead to the structuring of drainage catchments. The Morsott-Tebessa-Youkous (Chabro) collapsed basin corresponds to a subsiding depression framed by brittle structures and filled with thick deposits. Our work aims to unveil the neo-tectonic activity and reconstruct the morphometric evolution of the landscape and the drainage network of the basin. For this task, our investigation applies a quantitative analysis of geomorphic indices extracted from the DEM of the study area. We used a GIS-based approach to compile seven morphometric factors namely Integral Hypsometry (HI), the Sinuosity of mountain fronts (Smf), the Valley Floor width to height ratio (VF), the Asymmetry Factor (AF), Basin Shape index (BS), and the topography (T). All these thematic parameters were processed in a Geo-database to calculate the study area’s Relative Tectonic Activity Index (IRAT) as a result. The IRAT map was categorized into three classes. The result highlighted the distribution of relative tectonic activity in the region and unveiled some unknown faults. It associated the sinuosity of rivers and the deformation of the substratum with active tectonic anomalies. This research work succeeded in drawing up a new scheme of the neo-tectonic activity and morphostructural evolution in the collapsed basin.

5

Assessment of relative-active tectonics in rhumel-smendou basin (ne Algeria) – observations from the morphometric indices and hydrographic features obtained by the digital elevation model

Manchar Nabil, Hadji Riheb, Bougherara Ahmed, Boufaa Kamel

Geomatics, Landmanagement and Landscape

|

2022

|

no. 4

47--65

EN

The eastern Tell Atlas of Algeria is characterized by a complex neotectonic system including lateral strike-slips, and normal and reverse faults. The landscape of the Neogene basin of MilaConstantine acquired its shape due to the perpetual action of tectonic activity, and erosion processes. Neo-tectonics in this basin have affected the geometry of the stream network and the contemporary landscape topography. Our methodology evaluates the active tectonics in this mountainous region by a combination of drainage network and geomorphic indices, namely, the basin-shape index (Bs), stream-length gradient (SL), hypsometric integral (HI), mountain front sinuosity (Smf), basin asymmetry factor (AF), and valley-floor ratio (Vf). The calculated values of the six measured geomorphic indices were used to differentiate the distribution of faults function as well as the relative tectonic activity in the study area. The obtained results from the GIS-based multi-criteria analysis of these indices consist of the index of active tectonics (IAT). Hence, we defined four hierarchic degrees of IAT, namely, very high (VH), high (H), moderate (M), and low (L). The relative active tectonics represents an obvious correlation between morpho-structural features, tectonic activities, and uplift rates. It selects the morphotectonic features and landforms that interpret the tectonic events in the study area. Our results prove that this approach discerns the most active regions related to the neo-tectonic action in the RhumelSmendou drainage basin. The combination of geomatics and field surveys highlights the cliffs which are still rising by using the drainage patterns, the landform model, and the mountain range shape.

6

A combined field and automatic approach for lithological discrimination in semi-arid regions, the case of geological maps of bir later region and its vicinity, Nementcha mounts, Algeria

Chibani Abdelmouhcene, Hadji Riheb, Younes Hamed

Geomatics, Landmanagement and Landscape

|

2022

|

no. 4

7--26

EN

The Sahara’s Nememcha mountains chain suffers from a significant lack of large-scale geological information. In the Bir Later region with complex morpho-structural settings and arid climate conditions; geological maps have not been yet completed by competent authorities. However, this region harbours Algeria’s largest phosphate mine; with its reserves estimated at more than one billion tons of ore grading 20% phosphorus pentoxide. Geomatic-based techniques of Multisource Remote Sensing data allow the classification and identification of the lithologic features. The adopted method quarries the spectral signal, the alteration processes, and the thickness of the rocky banks. For this task, we apply Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), directional filters, and unsupervised classification (K-Means data) techniques to calibrate and correct Landsat 8 OLI and Sentinel-2A multispectral images. A petrographic study with field and laboratory work was carried out in order to confirm the machine description of the different facies. The results showed that the proposed lithology classification scheme can achieve accurate classification of all lithologic types, in the Cenozoic, Mesozoic, and Holocene deposits of the study area. The lithological map obtained from the GIS-RS-Processing is highly correlated with our field survey. Therefore, multispectral image data (Landsat 8 OLI and Sentinel-2A) coupled with an advanced image enhancement technique and field surveys are recommended as a rapid and cost-effective tool for lithologic discrimination and mapping. The experimental results fully demonstrated the advantages of the reliance on laboratory tests in the sensed lithology validation in an arid area.