Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunct... more Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunctioning of a pump. Especially for pumping stations with large rotodynamic pumps, the risk of malfunctioning should be minimized. For this reason, hydraulic investigations are performed prior to the construction of pumping stations to assess the amount of pre-swirl in the approach flow and if needed, to design local measures to decrease it. This article presents a test set-up of a simplified pump sump in which the pump performance characteristics are measured at a real pump for a wide range of predefined corotating and counterrotating swirl angles. The swirl angles are measured in a transparent model pump at scale 1:1 with a swirl meter at four bell diameters above the bell-mouth. The findings discussed in this paper provide insight in the relation between pre-swirl in the approach flow and pump performance.
Internal erosion phenomena occur in granular material when particles within the porous matrix are... more Internal erosion phenomena occur in granular material when particles within the porous matrix are transported by seeping fluid due to a hydraulic load that exceeds the erosion resistance of the material. Such phenomena pose a particular threat to embankment dams since in most cases they are concealed processes taking place within the dam's body or its foundation. However, these processes can evolve, cause sink holes and even lead to dam failure. This PhD thesis aims to accomplish a better quantitative understanding of two major internal erosion initiation processes, suffusion and concentrated leak mechanisms, which lead to both defect formation in a dam's body and its foundation and also high throughflow in dams subjected to internal erosion. This understanding has the potential to facilitate numerical modelling and expedite dam safety assessment studies.
Since the United States Environmental Protection Agency (USEPA) launched its "Green remediation" ... more Since the United States Environmental Protection Agency (USEPA) launched its "Green remediation" program and EU member states began to reassess their national regulations for environmental remediation in order to reach a Europe-wide consensus on policy and standards, the need for the sustainable removal of contaminants from brownfields has grown considerably. Concomitantly, the ability to calculate and assess the suitability as well as the environmental footprints and associated risks of a growing number of remediation techniques has become a priority. This thesis aims to evaluate two of the most widely-used free commercial tools for this purpose, SiteWise TMv.1 and SRT, for their practicability, quality and range of results and suitability specific to Swedish conditions. A number of ex-situ and in-situ methods are described in this thesis, a combination of which are then used to model twenty-six remediation scenarios for two documented contaminated sites in the Gothenburg region: the Bohus Varv site on the Götaälv bank and the Hexion site in Mölndal. A wide range of results for these models is presented, compared and analyzed, drawing further comparisons with a previous study and the zero-alternative, which can be used as an example to support sustainable decision making and to advocate the implementation of "gentle" remediation techniques to clear up contaminated sites. Based on the results from the both projects, it is concluded that: i. Remediation techniques requiring long distance residual handling have significant footprints except residual handling by train due to Swedish energy production conditions. ii. Residual handling with ship results in much higher SOx, NOx and particle release compared to the other alternatives. iii. Residual handling with truck results in high accidental risks. Finally, activities powered by electricity result in a reduced footprint compared to activities powered by fossil fuels, considering Swedish energy production conditions. The thesis concludes with a cross-benefit analysis of SRT and SiteWise TMv.1 , which recognizes their potential as tools for presenting accurate and reliable Life Cycle Assessment analyses with appropriate system boundary definitions and easy inventory analyses process. Their results provide valuable support to decision makers aiming at more sustainable remediation. The restricted range of remedial technologies with which SRT can model and the crucial adjustments needed to make this tool applicable and effective in Sweden are also evaluated, as are the certain expert knowledge need for modeling and the extensive data need for the SiteWise TMv.1 program. The limited practicability of SiteWise TMv.1 's final results on their own, with no comprehensive picture of the socioeconomic impact of each scenario is also regarded as a shortfall in real-life decision-making processes.
Journal of Geoscience and Environment Protection, 2013
The hydraulic behaviour of a rock material structure is a major feature for its design and safety... more The hydraulic behaviour of a rock material structure is a major feature for its design and safety assessment. Similar to all other physical problems, in order to enclose the governing equations systems and achieve a solution, the hydraulic characteristics of these materials need to be determined experimentally and implemented then into adopted thermo-dynamical models. This paper covers the process of the design, construction and operation of an experimental rig built for this specific purpose. Using the constructed large-scale permeameter, tests have been conducted. The non-linear hydraulic behaviour of various materials under extreme turbulent conditions, where Reynolds number reaches unprecedented values, has not been studied before. Preliminary results are presented and discussed.
Detecting internal erosion processes in porous media by an Arduino-based electrical impedance tom... more Detecting internal erosion processes in porous media by an Arduino-based electrical impedance tomography system developed on laboratory scale
A major cause of failure of embankment dams is internal erosion that is mostly driven by two diff... more A major cause of failure of embankment dams is internal erosion that is mostly driven by two different mechanisms, suffusion and concentrated leakage. Suffusion mechanism was studied for a cohesionless soil by laboratory experiments using an especially designed erosion apparatus which was capable of applying simultaneous hydraulic and mechanical loading while the erosion process was monitored. The main novel outcomes of the work are i) a new criterion for detecting the internal erosion initiation, ii) a modified theoretical model, namely the Modified Hydromechanical Envelop (MHE), for encountering the soil in-situ stresses and seepage-induced shear stress on internal erosion initiation and its continuation and iii) a semi-empirical constitutive law of internal erosion where the coefficients of this law were extracted experimentally. The MHE was proposed based on Mohr-Coulomb shear failure criterion. The constitutive law was defined as the rate of removal of mass due to the applicati...
Since the United States Environmental Protection Agency (USEPA) launched its “Green remediation&q... more Since the United States Environmental Protection Agency (USEPA) launched its “Green remediation" program and EU member states began to reassess their national regulations for environmental remediation in order to reach a Europe-wide consensus on policy and standards, the need for the sustainable removal of contaminants from brownfields has grown considerably. Concomitantly, the ability to calculate and assess the suitability as well as the environmental footprints and associated risks of a growing number of remediation techniques has become a priority. This thesis aims to evaluate two of the most widely-used free commercial tools for this purpose, SiteWise TMv.1 and SRT, for their practicability, quality and range of results and suitability specific to Swedish conditions. A number of ex-situ and in-situ methods are described in this thesis, a combination of which are then used to model twenty-six remediation scenarios for two documented contaminated sites in the Gothenburg reg...
Abstract Internal erosion phenomena are a major threat to all earthen structures, such as river l... more Abstract Internal erosion phenomena are a major threat to all earthen structures, such as river levees and dams. Studying these phenomena has been limited because they occur concealed inside the material, which makes them difficult to observe and monitor. Non-destructive geophysical monitoring techniques are powerful tools that can provide insight into the processes involved. For this reason, a test rig has been specifically designed to conduct three-dimensional electrical resistivity tomography of soil specimens undergoing internal erosion due to seepage. Two suffusion tests were conducted where the erosion evolution has been monitored. The time-series of eroded mass weight were then used to correlate the changes in three-dimensional resistivity distribution to the porosity change in media by means of Archie’s law. The results from the first suffusion test were used to calibrate Archie’s model parameters. It was found that the resistivity variations were able to predict changes in the porous matrix structure. The data obtained from the second test were used to validate the model parameters and confirmed that the time-lapse three-dimensional inverted resistivity images were able to successfully quantify the global erosion rate.
Since seepage-related problems are the main cause of more than fourty percent of dam failures, se... more Since seepage-related problems are the main cause of more than fourty percent of dam failures, seepage analysis is one of the most important stages in the design process of an embankment dam. Seepage factors must be monitored in the dam's body, abutments, and foundation during dam's operating life for evaluating safety and conducting risk assessments [1]. Most of e designing analysis is performed two-dimensionally and therefore, little attention is paid to seepage through abutments. On the other hand, the extension of the grout curtain inside the abutments, abutment material properties and dam site inhomogeneities, such as fault and crushed zones are inevitably neglected when performing 2D seepage analyses by this reason, 2D seepage analysis does not reflect real seepage factors and parameters [2]. In this case study, two and three-dimensional finite element (FE) models of an earth-fill dam are generated. Several steady state seepage analyses, as long term seepage behavior evaluation, are performed; the results are compared with the seepage monitored data from the instrumentation system installed in the dam body and foundation. It is concluded that conventional two-dimensional seepage models lead to results that are somewhat unrealistic; instead, three-dimensional (3D) models are much more representative of reality and can be used to evaluate seepage parameters in embankment dams.
IRAN 1. INTRODUCTION One of the most critical stages in designing embankment dams is evaluation o... more IRAN 1. INTRODUCTION One of the most critical stages in designing embankment dams is evaluation of pressure heads and hydraulic gradients in different parts of the dam body as well as evaluation of water discharge rates from the core and foundation. When seepage rates or hydraulic gradients increase unexpectedly or become uncontrolled, undesirable conditions may prevail to progress the piping or internal erosion that leads to dam instability or ultimate failure. The study of 77 embankment dam failures which have occurred in the United States until early 1980s indicates that seepage piping accounts for approximately 50% of all dam failures, the majority of which progress inside the dam embankment and foundation [1]. * Comparaison entre une analyse en deux et en trois dimensions de l'infiltration d'un barrage en enrochement construit dans une vallée étroite : étude de cas.
Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunct... more Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunctioning of a pump. Especially for pumping stations with large rotodynamic pumps, the risk of malfunctioning should be minimized. For this reason, hydraulic investigations are performed prior to the construction of pumping stations to assess the amount of pre-swirl in the approach flow and if needed, to design local measures to decrease it. This article presents a test set-up of a simplified pump sump in which the pump performance characteristics are measured at a real pump for a wide range of predefined corotating and counterrotating swirl angles. The swirl angles are measured in a transparent model pump at scale 1:1 with a swirl meter at four bell diameters above the bell-mouth. The findings discussed in this paper provide insight in the relation between pre-swirl in the approach flow and pump performance.
Internal erosion phenomena occur in granular material when particles within the porous matrix are... more Internal erosion phenomena occur in granular material when particles within the porous matrix are transported by seeping fluid due to a hydraulic load that exceeds the erosion resistance of the material. Such phenomena pose a particular threat to embankment dams since in most cases they are concealed processes taking place within the dam's body or its foundation. However, these processes can evolve, cause sink holes and even lead to dam failure. This PhD thesis aims to accomplish a better quantitative understanding of two major internal erosion initiation processes, suffusion and concentrated leak mechanisms, which lead to both defect formation in a dam's body and its foundation and also high throughflow in dams subjected to internal erosion. This understanding has the potential to facilitate numerical modelling and expedite dam safety assessment studies.
Since the United States Environmental Protection Agency (USEPA) launched its "Green remediation" ... more Since the United States Environmental Protection Agency (USEPA) launched its "Green remediation" program and EU member states began to reassess their national regulations for environmental remediation in order to reach a Europe-wide consensus on policy and standards, the need for the sustainable removal of contaminants from brownfields has grown considerably. Concomitantly, the ability to calculate and assess the suitability as well as the environmental footprints and associated risks of a growing number of remediation techniques has become a priority. This thesis aims to evaluate two of the most widely-used free commercial tools for this purpose, SiteWise TMv.1 and SRT, for their practicability, quality and range of results and suitability specific to Swedish conditions. A number of ex-situ and in-situ methods are described in this thesis, a combination of which are then used to model twenty-six remediation scenarios for two documented contaminated sites in the Gothenburg region: the Bohus Varv site on the Götaälv bank and the Hexion site in Mölndal. A wide range of results for these models is presented, compared and analyzed, drawing further comparisons with a previous study and the zero-alternative, which can be used as an example to support sustainable decision making and to advocate the implementation of "gentle" remediation techniques to clear up contaminated sites. Based on the results from the both projects, it is concluded that: i. Remediation techniques requiring long distance residual handling have significant footprints except residual handling by train due to Swedish energy production conditions. ii. Residual handling with ship results in much higher SOx, NOx and particle release compared to the other alternatives. iii. Residual handling with truck results in high accidental risks. Finally, activities powered by electricity result in a reduced footprint compared to activities powered by fossil fuels, considering Swedish energy production conditions. The thesis concludes with a cross-benefit analysis of SRT and SiteWise TMv.1 , which recognizes their potential as tools for presenting accurate and reliable Life Cycle Assessment analyses with appropriate system boundary definitions and easy inventory analyses process. Their results provide valuable support to decision makers aiming at more sustainable remediation. The restricted range of remedial technologies with which SRT can model and the crucial adjustments needed to make this tool applicable and effective in Sweden are also evaluated, as are the certain expert knowledge need for modeling and the extensive data need for the SiteWise TMv.1 program. The limited practicability of SiteWise TMv.1 's final results on their own, with no comprehensive picture of the socioeconomic impact of each scenario is also regarded as a shortfall in real-life decision-making processes.
Journal of Geoscience and Environment Protection, 2013
The hydraulic behaviour of a rock material structure is a major feature for its design and safety... more The hydraulic behaviour of a rock material structure is a major feature for its design and safety assessment. Similar to all other physical problems, in order to enclose the governing equations systems and achieve a solution, the hydraulic characteristics of these materials need to be determined experimentally and implemented then into adopted thermo-dynamical models. This paper covers the process of the design, construction and operation of an experimental rig built for this specific purpose. Using the constructed large-scale permeameter, tests have been conducted. The non-linear hydraulic behaviour of various materials under extreme turbulent conditions, where Reynolds number reaches unprecedented values, has not been studied before. Preliminary results are presented and discussed.
Detecting internal erosion processes in porous media by an Arduino-based electrical impedance tom... more Detecting internal erosion processes in porous media by an Arduino-based electrical impedance tomography system developed on laboratory scale
A major cause of failure of embankment dams is internal erosion that is mostly driven by two diff... more A major cause of failure of embankment dams is internal erosion that is mostly driven by two different mechanisms, suffusion and concentrated leakage. Suffusion mechanism was studied for a cohesionless soil by laboratory experiments using an especially designed erosion apparatus which was capable of applying simultaneous hydraulic and mechanical loading while the erosion process was monitored. The main novel outcomes of the work are i) a new criterion for detecting the internal erosion initiation, ii) a modified theoretical model, namely the Modified Hydromechanical Envelop (MHE), for encountering the soil in-situ stresses and seepage-induced shear stress on internal erosion initiation and its continuation and iii) a semi-empirical constitutive law of internal erosion where the coefficients of this law were extracted experimentally. The MHE was proposed based on Mohr-Coulomb shear failure criterion. The constitutive law was defined as the rate of removal of mass due to the applicati...
Since the United States Environmental Protection Agency (USEPA) launched its “Green remediation&q... more Since the United States Environmental Protection Agency (USEPA) launched its “Green remediation" program and EU member states began to reassess their national regulations for environmental remediation in order to reach a Europe-wide consensus on policy and standards, the need for the sustainable removal of contaminants from brownfields has grown considerably. Concomitantly, the ability to calculate and assess the suitability as well as the environmental footprints and associated risks of a growing number of remediation techniques has become a priority. This thesis aims to evaluate two of the most widely-used free commercial tools for this purpose, SiteWise TMv.1 and SRT, for their practicability, quality and range of results and suitability specific to Swedish conditions. A number of ex-situ and in-situ methods are described in this thesis, a combination of which are then used to model twenty-six remediation scenarios for two documented contaminated sites in the Gothenburg reg...
Abstract Internal erosion phenomena are a major threat to all earthen structures, such as river l... more Abstract Internal erosion phenomena are a major threat to all earthen structures, such as river levees and dams. Studying these phenomena has been limited because they occur concealed inside the material, which makes them difficult to observe and monitor. Non-destructive geophysical monitoring techniques are powerful tools that can provide insight into the processes involved. For this reason, a test rig has been specifically designed to conduct three-dimensional electrical resistivity tomography of soil specimens undergoing internal erosion due to seepage. Two suffusion tests were conducted where the erosion evolution has been monitored. The time-series of eroded mass weight were then used to correlate the changes in three-dimensional resistivity distribution to the porosity change in media by means of Archie’s law. The results from the first suffusion test were used to calibrate Archie’s model parameters. It was found that the resistivity variations were able to predict changes in the porous matrix structure. The data obtained from the second test were used to validate the model parameters and confirmed that the time-lapse three-dimensional inverted resistivity images were able to successfully quantify the global erosion rate.
Since seepage-related problems are the main cause of more than fourty percent of dam failures, se... more Since seepage-related problems are the main cause of more than fourty percent of dam failures, seepage analysis is one of the most important stages in the design process of an embankment dam. Seepage factors must be monitored in the dam's body, abutments, and foundation during dam's operating life for evaluating safety and conducting risk assessments [1]. Most of e designing analysis is performed two-dimensionally and therefore, little attention is paid to seepage through abutments. On the other hand, the extension of the grout curtain inside the abutments, abutment material properties and dam site inhomogeneities, such as fault and crushed zones are inevitably neglected when performing 2D seepage analyses by this reason, 2D seepage analysis does not reflect real seepage factors and parameters [2]. In this case study, two and three-dimensional finite element (FE) models of an earth-fill dam are generated. Several steady state seepage analyses, as long term seepage behavior evaluation, are performed; the results are compared with the seepage monitored data from the instrumentation system installed in the dam body and foundation. It is concluded that conventional two-dimensional seepage models lead to results that are somewhat unrealistic; instead, three-dimensional (3D) models are much more representative of reality and can be used to evaluate seepage parameters in embankment dams.
IRAN 1. INTRODUCTION One of the most critical stages in designing embankment dams is evaluation o... more IRAN 1. INTRODUCTION One of the most critical stages in designing embankment dams is evaluation of pressure heads and hydraulic gradients in different parts of the dam body as well as evaluation of water discharge rates from the core and foundation. When seepage rates or hydraulic gradients increase unexpectedly or become uncontrolled, undesirable conditions may prevail to progress the piping or internal erosion that leads to dam instability or ultimate failure. The study of 77 embankment dam failures which have occurred in the United States until early 1980s indicates that seepage piping accounts for approximately 50% of all dam failures, the majority of which progress inside the dam embankment and foundation [1]. * Comparaison entre une analyse en deux et en trois dimensions de l'infiltration d'un barrage en enrochement construit dans une vallée étroite : étude de cas.
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