An investigation into the seismic behaviour of dams using dynamic centrifuge modelling     

S. Saleh  S. P. G. Madabhushi 《Bulletin of Earthquake Engineering》2010,8(6):1479-1495

Dynamic response of dams is significantly influenced by foundation stiffness and dam-foundation interaction. This in turn, significantly effects the generation of hydrodynamic pressures on upstream face of a concrete dam due to inertia of reservoir water. This paper aims at investigating the dynamic response of dams on soil foundation using dynamic centrifuge modelling technique. From a series of centrifuge tests performed on model dams with varying stiffness and foundation conditions, significant co-relation was observed between the dynamic response of dams and the hydrodynamic pressures developed on their upstream faces. The vertical bearing pressures exerted by the concrete dam during shaking were measured using miniature earth pressure cells. These reveal the dynamic changes of earth pressures and changes in rocking behaviour of the concrete dam as the earthquake loading progresses. Pore water pressures were measured below the dam and in the free-field below the reservoir. Analysis of this data provides insights into the cyclic shear stresses and strains generated below concrete dams during earthquakes. In addition, the sliding and rocking movement of the dam and its settlement into the soil below are discussed.  相似文献   

Geologic relationships and mineralization of peralkaline/alkaline granite-syenite of the Zargat Na＇ am ring complex, Southeastern Desert, Egypt     

Gehad M. Saleh 《中国地球化学学报》2006,25(2):97-111

The Zargat Na’ am ring complex crops out 90 km NW of Shalatin City in the Southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. It is cut by two sets of joints and faults which strike predominantly NNW-SSE and E-W, and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. It consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills. The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFSM), such as Zr and Nb. The highest concentrations (1.5 wt% Zr, 0.25 wt% Nb, 0.6 wt% Σ REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartzhosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750 ￠ 10⁻⁶), Zr (2500 × 10⁻⁶) and REEs (1450 × 10⁻⁶). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions.  相似文献   

Mortar composite based on wet oxidative degraded cellulosic spinney waste fibers     

H. M. Saleh  S. B. Eskander  H. M. Fahmy 《International Journal of Environmental Science and Technology》2014,11(5):1297-1304

Textile industry has become an essential part of modern society, and waste production is an inevitable outcome of the developmental activities. Present paper outlines a direct approach toward a real problem of managing spinney waste fibers generated during textile industry. Simultaneously, shortage in landfill disposal space is another trouble associated with dumping of these hazardous wastes. Direct incorporation of these wastes into cementitious materials faces some disadvantages, so a partial oxidative degradation treatment was performed for those wastes in laboratory-scale experiments. Slurry resulted from the degradation process was incorporated into a mixture of cement/sand as hydrating agent to produce a mortar composite. Mechanical integrity and weight stability of the mortar composite produced were evaluated at the end of setting and hardening period under different variables. Based on the experimental results, the nominated mortar composite could be considered as an added-value product suitable for various applications, for example inert matrix for immobilization of some low and intermediate levels radioactive wastes, decorative tiles, building bricks, light concrete.  相似文献   

Geochemical assessment of groundwater contamination with special emphasizes on fluoride,a case study from Midyan Basin,northwestern Saudi Arabia   总被引：1，自引：0，他引：1  

Habes Ghrefat  Yousef Nazzal  Awni Batayneh  Taisser Zumlot  Haider Zaman  Eslam Elawadi  Abdulaziz Laboun  Saad Mogren  Saleh Qaisy 《Environmental Earth Sciences》2014,71(4):1495-1505

Water samples for chemical analyses were collected in January 2012. A total of 72 samples of groundwater were collected from 72 boreholes in the Midyan Basin, northwestern Saudi Arabia. Samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from American public health association. Geochemical analyses of the groundwater samples from Midyan Basin reveal the concentration of fluoride (F) between 0.98 and 2.1 mg/l. Other parameters, e.g, pH, EC, TDS, HCO₃, SO₄, NO₃, Cl, K, Na, Mg, and Ca have been found in a variable proportion. Among them, the concentration of EC, HCO₃, K, Na and Mg is higher than the permissible limits. According to thermodynamical considerations, most of the analysed samples are graded under-saturated with respect to calcite and fluoride, while saturation has been observed in some samples. The under-saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells. Fluoride concentration shows weak positive correlation with EC, TDS, Na, Cl, and SO₄. Factors controlling the concentration of fluoride (F) in the studied samples are the area climate, water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating, besides the anthropogenic activities in the area.  相似文献   

Pre- and post-seismic displacements associated with the Aswan 2011 earthquake (M = 4.2) derived from recent geodetic GPS data     

N. Abou-Aly  S. Abdel-Monem  M. Saleh 《Arabian Journal of Geosciences》2014,7(7):2547-2557

Due to the importance of Aswan area, Egypt, it has been selected for the present study. Since 1982, after the main shock of November 14, 1981 with M?=?5.6, several study programmes were initiated for monitoring seismicity and crustal movements at Aswan area (Tealeb 1996). Starting from 1997, GPS geodetic networks were established and observed many times in different campaigns. The observations are repeated twice a year. At the beginning of 2012, a moderate earthquake has occurred in the Aswan region with magnitude of 4.2 located at the southwest of the High Dam along Kalabsha fault. Before and after this event, these local geodetic networks were measured using GPS. Regional, Kalabsha-Sayal and Kalabsha networks were used in the present work. GPS data were processed using Bernese 5.0. The collected data before and after this event have shown that the area southwest of the High Dam and Kalabsha area suffered from stress and strain. The behaviour of the areas has changed after earthquake for pre-earthquake.  相似文献   

Forecasting areas vulnerable to forest conversion using artificial neural network and GIS (case study: northern Ilam forests,Ilam province,Iran)   总被引：1，自引：0，他引：1  

Saleh Arekhi  Ali Akbar Jafarzadeh 《Arabian Journal of Geosciences》2014,7(3):1073-1085

Forest conversion due to illegal logging and agricultural expansion is a major problem that is hampering biodiversity conservation efforts in the Zagros region. Yet, areas vulnerable to forest conversion are unknown. This study aims to predict the spatial distribution of deforestation in western Iran. Landsat images dated 1988, 2001, and 2007 are classified in order to generate digital deforestation maps which locate deforestation and forest persistence areas. Meanwhile, in order to examine deforestation factors’ investigation, deforestation maps with physiographic and human spatial variables are entered into the model. Areas vulnerable to forest changes in the Zagros forest region are predicted by a multilayer perceptron neural network (MLPNN) with a Markov chain model. The results show that about 19,294 ha forest areas are deforested in the last 19 years. The predictive performance of the model appears successful, which is validated using the actual land cover map of the same year from Landsat data. The validated map is found to be 94 % accurate. The validation is also tested using the relative operating characteristic approach which yielded a value of 0.96. The model is then further extended to predict forest cover losses for 2020. The MLPNN approach was found to have a great potential to predict land use/land cover changes because it permits developing complex, nonlinear models.  相似文献   

Drought risk assessment using remote sensing and GIS techniques   总被引：1，自引：0，他引：1  

Abdel-Aziz Belal  Hassan R. El-Ramady  Elsayed S. Mohamed  Ahmed M. Saleh 《Arabian Journal of Geosciences》2014,7(1):35-53

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.  相似文献   

A new velocity field from the analysis of the Egyptian Permanent GPS Network (EPGN)   总被引：1，自引：0，他引：1  

Mohamed Saleh  Matthias Becker 《Arabian Journal of Geosciences》2014,7(11):4665-4682

For studying recent crustal movements and their relation to earthquake occurrence in large scales, the National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt started in 2006 the establishment of the Egyptian Permanent GPS Network (EPGN). Beginning with 4 stations in 2007, 15 stations were operational at the end of 2011. In addition, a station in Alexandria of the French “Centre d'Études Alexandrines” (CEALX) was added as station to the EPGN. Nowadays, 16 stations are operational and an extension to 20 in the near future is expected. The collected EPGN data of the last 6 years are used in this work to throw light upon the present state of recent crustal movement of the whole of Egypt. Bernese software V. 5.0 was used for processing the collected data according to the IGS standards. In addition, selected IGS, AFREF, and EPN sites are processed for reference frame definition. In this first comprehensive analysis of the permanent network, a complete and consistent evaluation resulted in the first estimates of present day horizontal velocities and coordinate time series.  相似文献   

Can well-being between Sub-Saharan Africa (SSA) and Organization for Economic Cooperation and Development (OECD) member countries converge?     

Peter Adamu  Shivee Ranjanee Kaliappan  Abdalla Sirag  Ruth John Chenbap 《GeoJournal》2017,82(2):369-377

This study investigates the convergence of well-being between Sub Saharan Africa (SSA) and Organization for Economic Cooperation and Development (OECD) member countries during the period 1980–2014. The gap in living standard was examined from a steady state represented by the average income of OECD countries. Applying the unit root estimation technique to test for convergence with and without structural breaks, the result shows that; among a total of 43 countries studied, about 14 % are converging towards the average of OECD average. When the shock caused by the economic crisis of 2008 was factored into the analysis, the gains of about five countries out of the six converging disappeared. These results are disturbing owing to the fact that countries in the Asian region that started almost at the same level with SSA have converged to form a convergence club. Therefore, a lot more effort is needed from the government and stake holders in most countries in SSA to improve on the determinants of growth like good health care, quality institutions, better education and commitments to pursue developmental programmes which will boost the income of an average African to acquire better life.  相似文献   

Special issue on water resources in arid areas     

Osman Abdalla  Mingjie Chen 《Arabian Journal of Geosciences》2017,10(1):6

  相似文献