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Comparative Study of Slope Soils Analysis by Using limit Equilibrium and Finite Element Methods

International Journal of Geosciences 2022年第12期13卷 1089-1102页

作者： Kempena Adolphe watha ndoudy noël Obami Ondon Harmel Mbilou Urbain Gampio Antonio Olimpio Gonçalves Rafael Guardado lacaba Boudzoumou Florent Department of Geology Faculty of Sciences and Techniques Marien Ngouabi University Brazzaville Republic of Congo Mechanical Energy and Engineering Laboratory Higher National Polytechnic School Marien Ngouabi University Brazzaville Republic of Congo Department of Geology Faculty of Sciences Agostinho Neto University Luanda Angola Department of Geology Faculty of Mines and Geology Higher Institute of Mines and Metallurgy Moa Cuba

The slope soil analysis remains a corporate concern in construction activities. Because of its significance, the evaluation of slope soil stability has called widespread attention to several researchers all over the world. Many methods have been technologically advanced to evaluate the stability of slopes soils founded on distinct expectations and circumstances. Every method has specific benefits and limits. This work makes a comparison among safety factors and slip surfaces of slopes soils based on using limit Equilibrium and Finite Element methods. Therefore, SlIDE 6.0 and PlAXIS 8.0 software were used for limit Equilibrium and Finite Element methods, respectively. The computations of safety factors were performed for diverse shapes of slopes including different types of soils. Failure surfaces and values of safety factors obtained were compared for both methods used. It was noticed that the safety factors obtained from limit Equilibrium methods were larger than of which is obtained by the finite element code. Moreover, an important change is noticed between the slip surfaces obtained by using both approaches.

关键词： Slopes Soils Slip Surface limit Equilibrium Finite Element Factor of Safety

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Characterization of Gold Bearing Placers and Associated Minerals in the Elogo Region (North-West Congo Republic)

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Open Journal of Geology 2023年第5期13卷 287-305页

作者： Noël watha-ndoudy Prince Espoire Wamene Okoumel Timothée Miyouna Renaud Hermann Assouka Mpika Eddy Guembou Massala Guichel Souaty Mibantsa Kester Mayenga Joseph Victor Hell Boniface Kankeu Florent Boudzoumou laboratory of Geosciences Faculty of Science and Technology Marien Ngouabi University Brazzaville Congo National Institute of Forestry Research (IRF) Brazzaville Congo Gold Mines and Quarries of Congo MAC-CONGO Brazzaville Congo Institute of Geological and Mining Research (IRGM) Yaoundé Cameroun

The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed

关键词： Auriferous Placers Associated Minerals Correspondence Factor Analysis Principal Component Analysis Elogo Gold Exploration

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Soils Typology and Floristic Diversity of the Forest of the“Cite Scientifique”of Brazzaville,Congo

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Open Journal of Ecology 2018年第4期8卷 286-304页

作者： Jean de Dieu Nzila Victor Kimpouni Noel watha-ndoudy Michele Mercia Nanitelamio Yallo Mouhamed Salisou Diane Prudence Nguila-Ntsoko Ecole normale superieure Universite Marien NgouabiBrazzavilleCongo Institut national de recherche forestiere(IRF) BrazzavilleCongo Faculte des sciences et techniques Universite Marien NgouabiBrazzavilleCongo Ecole nationale superieure d’agronomie et de foresterie Universite Marien NgouabiBrazzavilleCongo

A study of the typology of soils and floristic diversity was carried out in the forest of the “Cité Scientifique” of Brazzaville. The study aimed to assess the influence of soil cover on the distribution of taxa. The study covers 18 plots of 625 m2 each, distributed in different soil profiles. The floristic inventory concerns the measurement of diameter of trees with dbh ≥ 10 cm and the counting of herbaceous and shrubs of dbh loristic composition reveals a total of 129 plant species distributed in 48 families dominated by Fabaceae and a preponderance of pioneer taxa. The Jaccard coefficients of similarity reveal a low degree of homology of woody plots, whereas for the flora as a whole, the floristic composition is heterogeneous. The Shannon biological diversity index of ligneous varies from 0.6 to 2, against a maximum diversity of 0.69 to 3. The Pielou index of ligneous (0.5 to 0.9) does not reveal any dominance. Soil cover consists of ferrallitic and podzol soils. Their texture is sandy, weakly structured, fragmentary polyhedral throughout the profile, but lumpy and/or nuciform at the surface and sub angular in depth. The porosity decreases proportionally with the depth and thickness of the horizons. The floristic analysis presents an ecosystem with a low degree of diversification for a high floristic richness. The preponderance of anthropization markers is a proof of its very advanced state of disturbance. The study shows that soil cover does not influence the distribution of timber. Indeed, the establishment and development of pioneer species are less prone to soil properties.

关键词： Congo Soil Cover Floristic Diversity Urban Forest Biological Diversity Index Distribution of Taxa

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