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Landslide susceptibility assessment in Constantine region (NE Algeria) by means of statistical models

Manchar N., Benabbas C., Hadji R., Bouaicha F., Grecu F.

Studia Geotechnica et Mechanica

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2018

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Vol. 40, nr 3

208--219

EN

The purpose of the present study was to compare the prediction performances of three statistical methods, namely, information value (IV), weight of evidence (WoE) and frequency ratio (FR), for landslide susceptibility mapping (LSM) at the east of Constantine region. A detailed landslide inventory of the study area with a total of 81 landslide locations was compiled from aerial photographs, satellite images and field surveys. This landslide inventory was randomly split into a testing dataset (70%) for training the models, and the remaining (30%) was used for validation purpose. Nine landslide-related factors such as slope gradient, slope aspect, elevation, distance to streams, lithology, distance to lineaments, precipitation, Normalized Difference Vegetation Index (NDVI) and stream density were used in the landslide susceptibility analyses. The inventory was adopted to analyse the spatial relationship between these landslide factors and landslide occurrences. Based on IV, WoE and FR approaches, three landslide susceptibility zonation maps were categorized, namely, “very high, high, moderate, low, and very low”. The results were compared and validated by computing area under the receiver operating characteristic (ROC) curve (AUC). From the statistics, it is noted that prediction scores of the FR, IV and WoE models are relatively similar with 73.32%, 73.95% and 79.07%, respectively. However, the map, obtained using the WoE technique, was experienced to be more suitable for the study area. Based on the results, the produced LSM can serve as a reference for planning and decision-making regarding the general use of the land.

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Mathematical approach for estimating the stability of geotextile-reinforced embankments during an earthquake

Dahoua L., Usychenko O., Savenko V. Y., Hadji R.

Mining Science

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2018

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Vol. 25

207--217

EN

The Bishop’s method gives a safety factor of circular slip surfaces in excellent agreement with those given by the reliable bi-dimensional slices analysis methods such as Spencer, Janbu or Morgenstern and Price methods. However, several significant disturbing factors are not considered by the simplified or rigorous Bishop’s method on which depends a lot of commercial computer programs. This paper discusses a mathematical approach to take into account changeable values of cohesion and friction angle in the Mohr–Coulomb criterion in order to consider the reduction of intrinsic characteristics; adapt a new parameter (Fs) to take into account the behavior under seismic solicitations, introduce a force (r) to take into account the of infiltrated part of water. Finally stabilizing forces generated by the geotextile layers (Geo) are statically engaged in Boshop’s polygon of forces. The result shows that the seismic factor gives the main disturbing force to the slope equilibrium; whereas the geotextile action gives the main stabilizing force. In other words, this modified Bishop’s method is proposed to calculate cases for which the original method could not be used.

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Use of slope failures inventory and climatic data for landslide susceptibility, vulnerability, and risk mapping in souk Ahras region

El Mekki A., Hadji R., Chemseddine F.

Mining Science

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2017

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Vol. 24

237--249

EN

Slope failures (SF) in mountainous terrain often occur during or after heavy rainstorms, resulting in the loss of life and damage to the natural and/or built environment. Assessing areas susceptible to SF is essential for land use planning in threatened areas. This article presents an didactic basedanalysis of the potential contribution to geo-spatial approaches for predicting SF qualitative exposure in mountainous environment. Its main aim is to assess the impact of the geologic, geomorphic, rainstorms, and anthropogenic factors in the initiation of SF in Zaarouria region. 219 events (1996–2016) were inventoried through images interpretation and field surveys and were compared to the physical parameters of the terrain to give a SF susceptibility index value using a simplified model. Vulnerability and risk maps are also established. The Standard deviation classification was used to delineate various susceptibility, vulnerability and risk zones, namely, nil, low, moderate and high. Field data on SF were employed to evaluate and validate the susceptibility zonation map. The results of this study demonstrate that SF are largely governed not only by geoenvironmental conditions but also by human activities, mainly roads and construction.

4

Original approach for the drilling process optimization in open cast mines; Case study of Kef Essenoun open pit mine Northeast of Algeria

Rais K., Kara M., Gadri L., Hadji R., Khochmen L.

Mining Science

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2017

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Vol. 24

147--159

EN

The drill ability is a fundamental factor for bit penetration rate (PR) in mining engineering. The ability to predict the performance of rock drills is important for drilling operations. Not a single parameter defines the drill ability of a rock. For this task, a considerable amount of fieldwork must be done to provide the necessary data i.e.: rock properties and drilling technologies. The main purpose of this research is to conduct an experimental study under varying rotation and pressures on the drilling bit for different geological formations. This paper presents a statistical analysis of process parameters of drilling in a phosphate mine in Jebel Onk, Tebessa, Algeria. Settings drilling parameters were determined by applying the design of experiments method. The level of importance of drilling parameters is determined by using analysis of variances. First, the teamwork determined the mathematical model for representative conditions of the phosphate mine of Jebel Onk. This mathematical model is a vital mathematical requirement for the operation engineers to deduce and determine the penetration rate according to the demands of work and to maximize the efficiency of the drilling machine and to minimize the bit wear in the abrasive layer.

5

Geophysical, geotechnical, and speleologic assessment for karst-sinkhole collapse genesis in Cheria plateau (NE Algeria)

Mouici R., Baali F., Hadji R., Boubaya D., Audra P., Fehdi C., Didier C., Stéphane J., Bruno A.

Mining Science

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2017

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Vol. 24

59--71

EN

Several sinkhole collapses were occurred in the many sites in urban areas and/or their rural periphery; in NE Algeria, in the last few years. The abrupt collapse causes damages to properties, infrastructures, and even lives. The most spectacular one occurred in February 2009 inside the Cheria city, Northwest of Tebessa department, with a diameter of more than a hundred meters. This abrupt collapse is due to a sudden rupture of the roof of a large underground karst cavity. It caused panic-stricken among the population living near the crater. In order to investigate the origin of this phenomenon, we combine several geophysical and geotechnical methods, such as Ground Penetrating Radar, Electrical Resistivity Tomography, Standard Penetration Test, Mechanical Drill Core, Cave Survey Photogrammetry, etc. It appears that each method may provide specific information. Their comparison allows to precise the results itself, the limits and the application field of each. Consequently a number of open karst voids and disturbed areas were detected in the study area. The results show that sinkholes originate from two different processes: a brutal collapse of karst voids located at shallow depth, by agravitational effect especially building surcharge on top of limestone. And progressive piping and erosion of the thick gravel cover, especially after storms making large depressions. The drawdown of the aquifer following intense pumping could have accelerated these processes. The extension plans of the study area could be established with this methodical acquaintance of the underground conditions of the karst cavities such as: occurrence, depth, geometry and dimensions.

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Slope stability analysis in open pit mines of Jebel Gustar career, NE Algeria – a multi-steps approach

Zahri F., Boukelloul M. L., Hadji R., Talhi K.

Mining Science

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2016

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Vol. 23

137--146

EN

Several types of instabilities can menace the personnel and equipment in the open cast mines. Their kinematicis dependent commonly on the nature, the structure, the fracturing and the strength of the rock mass. A scientific assessment vis-a-vis their equilibrium is suggested. For this task a considerable amount of field work must already carrying out to supply the necessary data ie: geometric, mechanic and geologic parameters. The main purpose of this research is identifying different modes of slope failures that may develop on the career “ENOF” of Jebel Gustar, by a multi-step analysis. For this task, i) a structural analysis; ii) an estimation of the rock mass and discontinuity mechanical properties, iii) a rating of the rock mass quality, iv) and a numerical simulation of the stability are procedurally used. The results matched well with the field observations. They proved the poor stability of the career, showing a typical example of a bad slope-design. The application of such approaches can help stabilizing the mine and ensure the safety and a sustainable production.