Assessment and Evaluation of Volcanic Rocks Used as Construction Materials in the City of Addis Ababa

Addis Ababa capital city of Ethiopia at an elevation of about 2000 m above mean  sea level is entirely covered with volcanic rocks, basalt, trachyte, ignimbrite and  rhyolite. Construction industry makes use these rocks extensively and  indiscriminately for structural loading, pavements, wall cladding, fencing, as cobblestone and masonry stones. The suitability of these rocks and their  petrographic and physico-mechanical properties evaluation becomes important for their aforementioned applications. So, field observation and sample collection for laboratory investigations were conducted on six selected target areas of the city periphery. In doing so, the compressive strength, open porosity, water absorption and density of various volcanic rocks were studied in the central laboratory of the Geological Survey of Ethiopia. Based on the physico-mechanical test results, some layers of ignimbrites and rhyolites are found to be the best for use in the  construction industry. Out of the six target areas, two areas located on the south and south eastern periphery of the Addis Ababa city were selected for possible dimension stone production. Therefore, these areas could be developed for  dimension stone quarry and exploitation of these rocks could be as rough  unprocessed building stone or better polished natural stones for a variety of uses.Keywords: Volcanic rocks, Dimension stone, Physico-mechanical properties, Petrography, Addis Ababa, Ethiopia

Geological and Geomechanical Properties of Abraha-Atsibha and Wukro rock-hewn churches and its surroundings, Tigray Region, Northern Ethiopia

Globally well-known ancient rock-hewn churches are present in Ethiopia in general and particularly in the central and eastern parts of Tigray regional state. They are important sites of heritage and tourism. Most of them are facing destabilization  problem in different degree due to natural and anthropogenic factors. Among the affected, two churches hewn into sandstone located near Abreha-Atsibaha and  Wukro (Kirkos/Cherkos church) in Tigray region were chosen for detailed study in  terms of geological and engineering geological condition of the rocks in to which  they are hewn. Both of them are affected by weathering and seepage. Both are  carved into Mesozoic Adigrat sandstone that occupy higher elevations in  topography, red in color and with iron and silica-rich alternating bands. Petrographic data suggest that the rock is dominated by quartz followed by feldspars; opaque and heavy minerals; pore spaces and carbonate/iron/silica cement. The rock is  characterized by low to medium unconfined compressive strength. The alternating  bands with varying mineralogical composition differ in mechanical properties and are responding differently to weathering and erosion. This is resulting in the  development of minor spalling, pitting etc in the pillars, walls and roofs of the  churches. Keeping the geological condition in view remedial measures are to be planned to minimize deterioration with time.Keywords: Geological, Geomechanical, Rock hewn-Church, Abraha-Atsibaha, Tigray, Ethiopia

gis based landslide susceptibility evaluation using analytical hierarchy process ahp approach the case of tarmaber district ethiopia

Landslides are one of the natural threats that often result in great loss of life and destruction of property in Ethiopia. One of the areas that is affected by landslides of different types and sizes is the Tarmaber district in the rift margin in the central part of Ethiopia. Keeping in view the cause and effect relationship and mitigation, Analytical Hierarchy Process (AHP) approach is used in the present case to understand the possible causes for landslides. Based on AHP, landslide susceptibility map is produced for Tarmaber using field survey data, remote sensing data, and geographic information system tools. The factors considered in the present case that can influence landslides are lithology, proximity to fault, land use, proximity to drainage, slope gradient, aspect and elevation. The results are validated with the inventory of landslide occurrences. The landslide susceptibility index (LSI) is calculated using the weighted -linear combination (WLC) technique based on the assigned weight and rating given by the AHP method. The accuracy of the results verified using the existing landslide locations is about 88.6%.The landslide susceptibility zonation map has identified our classes/zones: very high (29%), high (44%), moderate (20.0%) and low (7%). Keywords: Landslide susceptibility; Analytical Hierarchy Process (AHP); Tarmaber; Ethiopia

Comparative Analysis of Aerial Photography with Instrumental Survey

At present, in Kuzbass, various methods of automation of plane surveys in open mining are used. In most cases, the choice of method depends on the material base of the enterprise and the professionalism of the performers. Typically, the work on the surveying automation consists in using electronic tachometers, which reduce time and simplify field and office work. However, the use of electronic tachometers remains the human factor and does not allow solving the problem of displaying the situation throughout the open pit at one physical moment of time. Aerial photography (AP) significantly increases the performance of plane surveys and makes it possible to most fully and reliably display the information about the surface and ensure the safety of fieldwork. The article presents a comparative analysis of the accuracy of constructing a digital terrain model obtained during aerial photography by AN-2 aircraft and instrumental survey performed with electronic tachometer Leica TS 06 plus, by example of surveying a trench of section № 1 at Olzherassky open pit in the Kemerovo region. The advantages and disadvantages of AP from an airplane and prospects of using AP from an unmanned aerial vehicle (UAV) are given

Landslide susceptibility mapping in the Adwa Volcanic Mountain Plugs, Northern Ethiopia: a comparative analysis of frequency ratio and analytical hierarchy process methods

AbstractLandslides are a widespread occurrence in various regions across the globe, and Ethiopia serves as a typical example. The objective of this research was to develop and evaluate a landslide susceptibility map (LSM) using two different approaches: the frequency ratio (FR) and analytical hierarchy process (AHP). The suitability and effectiveness of both approaches were assessed for the specific study area. In the initial phase, a total of 175 past landslides, covering an area of 13.09 km2, were identified and mapped for further analysis. Eight causative factors, including elevation, slope steepness, slope aspect, lithology, distance from fault and stream, precipitation, and land use/land cover, were selected and mapped accordingly. Subsequently, a landslide susceptibility index (LSI) was calculated based on the relative influence of these factors on the recorded past landslides. The resulting LSMs were then categorized into five zones representing varying degrees of susceptibility: very low, low, moderate, high, and very high. For the LSM derived from the FR approach, the very high and high susceptibility zones accounted for 16.65 km2 (7.58%) and 79.96 km2 (36.4%) of the total area, respectively. Conversely, for the LSM derived from the AHP approach, these values were 21.9 km2 (9.99%) and 68.9 km2 (31.37%). Generally, both the FR and AHP approaches yielded comparable results. The LSMs were validated using the area under the curve (AUC) method. The FR model exhibited higher accuracy and prediction rates, with values of 0.807 and 80.7%, respectively, compared to the AHP model with values of 0.756 and 75.6%, respectively. These generated LSMs offer valuable insights for identifying and addressing the requirements of landslide hazard mitigation and adaptation

Technogenic Rock Dumps Physical Properties' Prognosis via Results of the Structure Numerical Modeling

Understanding of internal structure of the technogenic rock dumps (gob dumps) is required condition for estimation of using ones as filtration massifs for treatment of mine wastewater. Internal structure of gob piles greatly depends on dumping technology to applying restrictions for use them as filtration massifs. Numerical modelling of gob dumps allows adequately estimate them physical parameters, as a filtration coefficient, density, etc. The gob dumps numerical modelling results given in this article, in particular was examined grain size distribution of determined fractions depend on dump height. Shown, that filtration coefficient is in a nonlinear dependence on amount of several fractions of rock in gob dump. The numerical model adequacy both the gob structure and the dependence of filtration coefficient from gob height acknowledged equality of calculated and real filtration coefficient values. The results of this research can be apply to peripheral dumping technology

Slope Stability Assessment and Underground Mine Design Analysis of Achibo-Sombo Underground Conventional Coal Mine, Southwest Ethiopia

We report the slope stability assessment and underground mine design analysis results for the first of its kind conventional Achibo-Sombo underground coal mine from Ethiopia. Based on the RQD, RMR and Q classification system, the rocks in the mine are of poor to fair rock quality and are classified into category I (25 MPa). Joint space and aperture are ranging from few mm to cm with E-W, NNW-SSE and N-S orientations and low to very low persistence from 50 cm to 2 m. The factor of safety calculated using CMRI, Salamon-Munro, Greenwald, Obert and Duvall, and Bieniawsk methods for the existing pillars for category I is 1.37, 4.39, 2.21, 3.58, 4.76; category II 2.25, 4.39, 7.76, 12.52, 16.72; and category III 3.21, 4.39, 13.72, 22.26, 29.58 respectively. The factor of safety calculated again for the newly proposed design using the same methods is 1.05, 3.83, 1.91, 2.99, 3.8 for category I; 1.65, 3.17, 5.48, 8.55, 10.02 for category II and 2.20, 2.63, 7.91, 8.26, 14.25 for category III respectively. The extraction percentage has increased from 24.2 % (for the existing) to 31%, 41% and 52% for I, II and III categories respectively

Slope Stability Assessment and Underground Mine Design Analysis of Achibo-Sombo Underground Conventional Coal Mine, Southwest Ethiopia

We report the slope stability assessment and underground mine design analysis results for the first of its kind conventional Achibo-Sombo underground coal mine from Ethiopia. Based on the RQD, RMR and Q classification system, the rocks in the mine are of poor to fair rock quality and are classified into category I (25 MPa). Joint space and aperture are ranging from few mm to cm with E-W, NNW-SSE and N-S orientations and low to very low persistence from 50 cm to 2 m. The factor of safety calculated using CMRI, Salamon-Munro, Greenwald, Obert and Duvall, and Bieniawsk methods for the existing pillars for category I is 1.37, 4.39, 2.21, 3.58, 4.76; category II 2.25, 4.39, 7.76, 12.52, 16.72; and category III 3.21, 4.39, 13.72, 22.26, 29.58 respectively. The factor of safety calculated again for the newly proposed design using the same methods is 1.05, 3.83, 1.91, 2.99, 3.8 for category I; 1.65, 3.17, 5.48, 8.55, 10.02 for category II and 2.20, 2.63, 7.91, 8.26, 14.25 for category III respectively. The extraction percentage has increased from 24.2 % (for the existing) to 31%, 41% and 52% for I, II and III categories respectively

Technogenic Rock Dumps Physical Properties' Prognosis via Results of the Structure Numerical Modeling

Understanding of internal structure of the technogenic rock dumps (gob dumps) is required condition for estimation of using ones as filtration massifs for treatment of mine wastewater. Internal structure of gob piles greatly depends on dumping technology to applying restrictions for use them as filtration massifs. Numerical modelling of gob dumps allows adequately estimate them physical parameters, as a filtration coefficient, density, etc. The gob dumps numerical modelling results given in this article, in particular was examined grain size distribution of determined fractions depend on dump height. Shown, that filtration coefficient is in a nonlinear dependence on amount of several fractions of rock in gob dump. The numerical model adequacy both the gob structure and the dependence of filtration coefficient from gob height acknowledged equality of calculated and real filtration coefficient values. The results of this research can be apply to peripheral dumping technology

Geo-Resources Recycling as the Way of Mining Wastes Disposing

Scientific and technological progress envisages the solving the most important problems in the main areas of mineral processing, leading to the perfection of technological processes, improving quality indicators and reducing the cost of production. Rational use of minerals at the stages of their extraction and enrichment is a single indivisible problem, the main task of which is the fullest use of basic and rare minerals. Geo-resources include mineral deposits and subsurface materials (solid, liquid, gaseous, mixtures), underground space (cavity), subsurface energy (static, geo-dynamic, geomagnetic). Geo-resources are provisionally recognized as geoinformation, characterized by various attributes and properties of subsurface material (minerals, overburden, etc.), and the other geo-resources, including streams migrating into the depths (fluids, magma, etc.). It is clear that mineral resources are part of the subsurface material. Therefore, the most important aspect of geo-resources development today is the initiation of recycling of their industrial processing