Papers by Nadhir Al-Ansari
Mesopotamia Journal of Agriculture
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Journal of Earth Sciences and Geotechnical Engineering
Tailings’ Dams are mining waste impounding structures. They differ from conventional dams in purp... more Tailings’ Dams are mining waste impounding structures. They differ from conventional dams in purpose, design and operation. Percentage wise their failures are higher and posing considerably more safety concerns, causing long lasting devastation on communities, environment, and animal and plant ecosystem. Two basic types of embankment tailings structures are used for tailings impoundments; the Retention Dams and the Raised Dams. Retention dams are built in one operation to a full height, while construction of Raised Dams is a continuous process lasting for the whole useful life of the mine. Raised Dams are favored over Retention dams as they can be enlarged and expanded as the extraction works continue with time. Raised embankment dams themselves can be of three alternative designs according to the method used in construction; the Downstream, Upstream and Centerline structures. This designates the direction in which the embankment crest moves in relation to the initial embankment at ...
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Journal of Earth Sciences and Geotechnical Engineering
Seismic instrumentation of dams and reservoirs sites is accepted today as a valuable tool to unde... more Seismic instrumentation of dams and reservoirs sites is accepted today as a valuable tool to understand significant seismic hazards facing existing dams or future planed dams. With the advent of digital seismic accelerometers and recorders, it can now be used today as an integral part of dam safety monitoring systems. Outputs of these instruments help in understanding the dynamic response of dams during earthquake, assessing the damage caused by such events and determining required upgrading works necessary for existing dams and designing of safer dams in the future. Measuring and recording by strong motion seismographs covers the induced Peak Ground Acceleration (PGA), velocity and displacement recorded on time scale to indicate the intensity and frequency of ground vibration at the site during seismic events. Seismometers for such measurements and recordings have undergone considerable evolution and there exist today a variety of these instruments with high degree of refinement wh...
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Journal of Earth Sciences and Geotechnical Engineering, 2020
Embankment dams undergo aging process due to the impact of different factors which can be attribu... more Embankment dams undergo aging process due to the impact of different factors which can be attributed to geology of the site, design of the dam, materials selection and procedures followed in constructions. In the foundation the presence of faults or shearing planes, karst, compressible clayey material, soluble rock, and soft rock may establish conditions leading to high total settlement or differential settlements of the dam and its cracking. Deficient and deteriorating seepage control measures such as grout curtains or diaphragms enhance seepage flow leading to internal erosion and piping which endanger dams’ stability. Improper filling materials used such as dispersive clays and gap graded granular material show their bad influence after long time by creating conditions inducive to internal erosion and piping. Use of improperly designed and placed filter zones and drainage blankets can end in clogging of such filters and drainage blankets leading to the rise of the phreatic surface level and increasing uplift causing again conditions of internal erosion and piping and undermine stability. This work attempts to give an overview of these conditions and cite many case studies of rehabilitation works carried out in dams after long years of service. The conclusion reached is that rehabilitation works if done early when problems are discovered play well to elongate the service life of dams, but normally they require large investments. Sooner or later owners of such old dams will come to realize that more rehabilitation works, neither technically nor economically, are feasible and that more of such works are not possible. In which case they will come think seriously of decommission such expired dams.Validerad;2020;Nivå 1;2020-06-23 (alebob)</p
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Journal of Earth Sciences and Geotechnical Engineering, 2020
Concrete dams age as all man-made structures. Being subject to various external influences and in... more Concrete dams age as all man-made structures. Being subject to various external influences and internal reactions their ability to withstand them diminishes with time. Description of these factors are given here. The manifestations of aging signs are cracking, expansion, spalling and scaling of concrete surfaces, change of color and efflorescence, gelatinous discharge, crumbling of concrete masses, in addition to abrasion and cavitation of surfaces. The mechanisms of the actions leading to these damages are described and supported by many examples and case studies. The general conclusion drawn is that nothing can be made to extend the lives of old dam indefinitely, but a lot can be done to elongate their useful service with repair and upgrading works until technical considerations prove them unfeasible or their cost become prohibitive.Validerad;2020;Nivå 1;2020-06-23 (alebob)</p
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Journal of Earth Sciences and Geotechnical Engineering, 2020
Earthquakes may cause failure or profound damage for dams. Factors contributing to this are, magn... more Earthquakes may cause failure or profound damage for dams. Factors contributing to this are, magnitude on the Richter scale, peak horizontal and vertical accelerations, time duration, in addition to the epicentral distance, nature of foundation rock, criteria of the design, and finally, if appropriate type of dam and materials has been used. Extensive lists of dam failures and damaged once are presented with many case histories. Most failed dams were tailing dams or hydraulic fill dams or small earth fill dams, which reflect the weight of the design and construction factors. Embankment dams, normally, are less tolerant to ground shacking than concrete dams. While rockfill and RCC dams have shown good performance. The developments of design methods and criteria are traced here, from the early use of the pseudoptotic method to the more rational dynamic analysis, which is used nowadays making construction of very large safe dams in seismic regions possible. The method adopts peak ground accelerations from anticipated earthquakes as inputs to the analysis which produce a full spectrum of the factor of safety during any considered event. This has led to increased use of seismic instrumentation to produce seismographs of actual events in the free field, and on dams hit by earthquakes for comparison with outputs of this analysis and for future use for similar dams in similar circumstances, and to decide on rehabilitation measures. The safety levels to which any dam is to be designed are defined in terms of the Maximum Credible Earthquake, Safety Evaluation Earthquake, Maximum Design Earthquake and other similar terms. Dam repairs after sustaining earthquake damages are described in real cases and upgrading of older dams to withstand higher expected seismic events are also treated here and supported by case histories.Validerad;2020;Nivå 1;2020-06-23 (alebob)</p
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Journal of Earth Sciences and Geotechnical Engineering, 2019
Iraq has been involved with two major wars in 1991 and 2003 (Gulf war I and II), which resulted i... more Iraq has been involved with two major wars in 1991 and 2003 (Gulf war I and II), which resulted in leaving large amounts of wrecked tanks, vehicles, weapons and ammunition. A considerable amount of the military waste contains depleted uranium (DU), which is a by-product of the enrichment of natural uranium for nuclear reactor-grade or nuclear weapons-grade uranium. DU used during the second Gulf war is more than 1100 to 2000 tons. This has serious effects on humans in Iraq and the environment. There is no national or international program for cleaning Iraq of DU wastes. To protect humans and the environment, three locations for disposals were suggested according to the geological conditions. These locations fulfill the requirements so that radioactive waste does not affect human life and the environment. To use these sites there should be proper design for the landfills so that it can perform for long period of time.Validerad;2019;Nivå 1;2019-09-02 (johcin)</p
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Journal of Earth Sciences and Geotechnical Engineering, 2020
Dams construction is an old art practiced by man since thousands of years. History of dams shows ... more Dams construction is an old art practiced by man since thousands of years. History of dams shows great innovations in this field, but failure cases, however, indicate gaps in human knowledge of safety measures that could have stopped such failures. Available statistics show of a great boom in building dams during the past century and indicate at the same time large number of failures associated with losses in human lives and material damage. Uses of these dams during this period, apart from flood control and storing water for irrigation were also for hydropower generation, navigation, drinking water supply, recreation and in mining operations as tailing dams. Reduced dam safety leading to failures, accidents and higher safety hazards were caused by insufficient knowledge of the geological conditions and in using wrong or deficient foundation treatment. Dam safety was compromised in cases of insufficient hydrological data and design of inadequate spillways. Misinterpretation of the seismic conditions of the area and adopting seismic criteria compatible with such seismic conditions is also added as one more reasons of failures. Human mistakes and errors have undermined safety in many cases in the operation of dams leading to grave safety issues including many failures. Safety hazards also were exasperated by increasing population and land use in the downstream areas of dams and by failing to do necessary inspection and maintenance or upgrading works. More emphasis over dam safety measures is needed now in our existing dams and in their future development of dams if they are to continue delivering their benefit without causing harm to human communities.Validerad;2020;Nivå 1;2020-06-23 (alebob)</p
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Open Journal of Geology, 2022
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Journal of Earth Sciences and Geotechnical Engineering, 2020
When a dam is built, its safety becomes a constant concern for the owner, the public and for gove... more When a dam is built, its safety becomes a constant concern for the owner, the public and for governments. Therefore, continuous observation through routine inspections and safety reviews become necessary. Acting as protectors of public safety, governments and professional organizations save no effort in the promulgation of legislations and laying out guidelines for such inspections and reviews. These issues are discussed here starting with the basic first step of visual inspections by the operators and the follow up of detailed safety reviews by specialists. Careful visual inspections assisted by instrumentation measurements may reveal an early negative issue such as, but not limited to, increased seepage, increased uplift pressure, signs of weakness like cracking in the body of the dam, or dams’ slope sloughing, and even damaged hydraulic control equipment. Documenting and reporting these observation helps in taking remedial measures in good time and may lead to more intensive safe...
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Geological hazards that can face dams are very important in deciding their safety and successful ... more Geological hazards that can face dams are very important in deciding their safety and successful performance during their lifetime without excessive and costly repairs. Recognizing such hazards mus ...
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Iraq relies greatly on the water of the Tigris and Euphrates Rivers. These rivers rise in Turkey.... more Iraq relies greatly on the water of the Tigris and Euphrates Rivers. These rivers rise in Turkey. As far as the water quality of the Tigris River, when it enters the Turkish- Iraqi border is consid ...
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Dangerous occurrences affecting dams take multiple forms, but seepage caused cases are the most n... more Dangerous occurrences affecting dams take multiple forms, but seepage caused cases are the most numerous. Some of the cases are related to the geology of the foundation and the magnitude and type o ...
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Oilfield in southern part of Iraq, Kuwait and Saudi Arabia represent subsurface anticlines within... more Oilfield in southern part of Iraq, Kuwait and Saudi Arabia represent subsurface anticlines within the folded zone. Iraq forms the extreme northeastern parts of the Arabian Plate. It is divided into ...
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Most of the Mesopotamian Plain is covered by Quaternary sediments among which the flood plain sed... more Most of the Mesopotamian Plain is covered by Quaternary sediments among which the flood plain sediments of the Tigris and Euphrates rivers are the most dominant parts. Aeolian sediments; however, a ...
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Euphrates and Tigris Rivers are the longest Rivers in southwest Asia. The main utilizers of the w... more Euphrates and Tigris Rivers are the longest Rivers in southwest Asia. The main utilizers of the water of these rivers and tributaries are Turkey, Syria, Iran and Iraq. The two rivers rise in Turkey ...
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The Mesopotamian Plain is part of the large Mesopotamia which extends in Iraq and surrounding cou... more The Mesopotamian Plain is part of the large Mesopotamia which extends in Iraq and surrounding countries. The plain is almost flat and vast lowland, which has clearly defined physiographic boundarie ...
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The main material with economic potential in the plain is the clay. The clay is used for brick pr... more The main material with economic potential in the plain is the clay. The clay is used for brick production; either with modernized technology or primitive industry. It is also used for cement indust ...
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The Mesopotamian Plain is part of the Mesopotamia which extends for vast area bigger than the pla... more The Mesopotamian Plain is part of the Mesopotamia which extends for vast area bigger than the plain. The Mesopotamian Plain is covered totally by Quaternary sediments among which the fluvial origin ...
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Papers by Nadhir Al-Ansari
encourages researchers to study the details water environment in different aspects.Consequently, this study objective to evaluate thewater quality in the Euphrates River through adopted 11 physicochemical parametersmeasured at 16 locations during the 3 years (2009–2011) for both seasons (dry and wet). In this study, the water quality indexmodel (WQIM)was calculated aftermodifying the weighted arithmetic method
to define as MWQI. The chosen parameters were comprised of Cl, SO4, HCO3, NO3,Na, K, Ca, Mg, TH, TDS, and EC. For the river section of locations (L.1–L.10),all readings of the selected parameters (expected HCO3) were increased more and more. Then, all concentrations of parameters were recorded the high increasing after location (L.10) at locations (L.11–L.14). The concentrations situation of HCO3 were verse vice at all locations. For the average values of 3 years (wet, dry, total), the MWQI of section length of the Euphrates River at locations (L.1–L.10) were classified as good water quality (class, C-II). The river section at locations (L.11–L.16, excepted L.13) was classified as poor water quality (class, C-III), while the location (L.13) was classified as very poor (class, C-IV). The interpolation prediction maps of the average readings (total, dry, and wet) of the Euphrates River were output in GIS using the interpolation model of IDWM.