Rogério Mota | National Laboratory for Civil Engineering (original) (raw)

Papers by Rogério Mota

Proceedings, 2013

Landfills contain basal lining systems that include composite liners, among which a geomembrane (... more Landfills contain basal lining systems that include composite liners, among which a geomembrane (GM). The success of these systems depends mainly on the GM performance, which acts as the primary barrier to contaminants migration. GM performance is conditioned by the presence of holes, which represent preferential pathways for leachate migration. An equipment was developed to detect holes in geomembranes. It is based on the geophysical resistivity method and aims to overcome the main disadvantages of the existing methods for GM holes detection, mainly time spent to perform the tests and the associated high costs. Several prototypes were already developed and were tested at small scale in laboratory. The final version, which is the model for the equipment under construction, was already successfully tested at laboratory small scale pilot plant and in a large pilot plant at Laboratório Nacional de Engenharia Civil, I.P. (LNEC) campus. This paper presents the prototypes development and results so far obtained.

Near Surface Geophysics, 2010

Porosity and degree of saturation-or the water content-are important parameters for hydrogeologic... more Porosity and degree of saturation-or the water content-are important parameters for hydrogeological, geotechnical and environmental studies. Geophysical methods, especially the resistivity method, are routinely employed to study the spatial variations of these parameters. Resistivity is highly influenced by the presence of water in pore spaces and hence is well suited for studying the presence of fluids on a site and its saturation condition. However, the non-uniqueness of the solution of resistivity models has led to the joint use of more than one geophysical method in order to reach more accurate geophysical models. In this research, we combined resistivity and seismic refraction profiles. The integration of these methods was particularly aimed to obtain 2D sections for estimating the porosity, water saturation and volumetric water content rather than to obtain a better geophysical solution. Independently inverted resistivity and P-wave refraction sections are the input data to an iterative analysis process using simulated annealing. Empirical equations taken from the literature are used to relate both the seismic velocity and the electrical resistivity with porosity and water saturation. Several parameters, such as the resistivity of water and clay; the velocity of water, clay, air and matrix; clay percentage and Archie's parameters remain constant throughout the process. The values considered for each parameter are derive from both the literature and laboratory measurements. Resistivity and seismic refraction profiles were performed on a site located within the LNEC campus. At this site, field measurements of void ratio and volumetric water content were performed at different depths. Soil samples were also collected at three different depths in order to perform laboratory measurements of these parameters and to determine soil composition. The laboratory results were compared with the 2D sections of each parameter. The proposed approach was also applied to two other locations with different and well characterized geology. These tests also allowed us to characterize the dependency of the clay content on the resistivity. This research has potential fields of application in environmental studies, in particular, the determination of probable pathways of pollutants; in hydrological investigations, where it can be useful to transport of nutrients studies; and in geotechnical studies, where, for example, it will be able to give a continuous image of the saturation degree of an embankment. ties and its subsurface structure, i.e., it reduces the non-uniqueness of the solution. This has led to the joint application of different techniques in geophysical prospecting. The joint inversion of different geophysical data usually needs a common parameter. For resistivity and seismic velocity, there are two ways to perform the joint inversion: by the petrophysical approach, in which both the porosity and the water saturation are the connecting link (e.g., Wempe 2000; Berryman et al. 2002), or by the structural approach, in which the pattern of the variation in properties is used as a common constraint (e.g., Haber and Oldenburg 1997), Gallardo and Meju (2003), de Nardis et al.

Journal of Applied Geophysics, 2004

... of a low resistivity fluid, the most obvious candidate being waste leachate diluted by ground... more ... of a low resistivity fluid, the most obvious candidate being waste leachate diluted by groundwater. ... Outcrop conditions preclude the geological detection of deep lying horizontal fracture zones. ... In any case, the spread of the leachate contamination is limited downward to around ...

International Journal of Environment and Waste Management, 2009

The evaluation of vibrations induced to build structures is one of the main concerns when dealing... more The evaluation of vibrations induced to build structures is one of the main concerns when dealing with blast works. EDP, the main Portuguese producer of electricity is presently incrementing energy production in some old hydropower dams by installing new production plants. The need for not disrupting production during the upgrading works causes some concerns related with vibrations induced to the production engines. Vibration estimation was performed in two of these dams, constructed in a granite environment, by performing controlled blasts. For each dam site, some vibration transmissivity laws were developed with the fitting process.

The presence of high vulnerable karstic systems in areas of intense human activities often result... more The presence of high vulnerable karstic systems in areas of intense human activities often results in the degradation of existing groundwater quality status. The water quality (WQ) protection and improvement, as required by the WFD (Water Framework Directive), depends on a correct prioritisation of the most relevant impact pollution sources to be identified within complex multi-stressor conditions. This paper presents a methodology that combines the use of hydrogeology, WQ and quantity data, and geophysical methods to access the human activities' impacts upon the water cycle, focusing on the WQ of a karstic system. The procedure was applied to a section of the Portuguese karstic Querença-Silves aquifer, under FCT PROWATERMAN project PTDC/AAC-AMB. During this study an interpretation of the possible interconnections between pollutant sources, their pathways and local surface-groundwater connections was analysed, based on data obtained from field campaigns. As a result of this stud...

Environ. Process., 2014

The presence of highly vulnerable karstic systems in areas of intense human activities often resu... more The presence of highly vulnerable karstic systems in areas of intense human activities often results in the degradation of existing surface-and groundwater quality status. Water quality protection and improvement, as required by the Water Framework Directive (WFD), depends on correct identification and prioritisation of the most relevant pollution sources within complex multi-stressor conditions. This paper presents a methodology that combines the use of hydrogeology, water quality and quantity data, and electrical resistivity tomography methods to access different anthropogenic impacts upon the water cycle, focusing on the water quality of a section of the Portuguese karstic Querença-Silves aquifer. During this study an interpretation of the possible interconnections between pollutant sources, their pathways and local surface-groundwater connections was made, based on data obtained from field campaigns. As a result of this study, the areas with more interconnection between surfaceand groundwater were identified, namely the influent sites from the local stream into the aquifer. The impact of the diffuse pollution sources was verified at the monitoring points, especially those located downstream of large farming plots. Pollution in this karst aquifer results from seepage through agricultural areas and infiltration at the influent points of the stream. This aspect of stream influence upon the aquifer means that pollution sources located upstream of the area of the aquifer (e.g., a WWTP-Wastewater Treatment Plant) can also contribute to the aquifer pollution.

Proceedings, 2013

Landfills contain basal lining systems that include composite liners, among which a geomembrane (... more Landfills contain basal lining systems that include composite liners, among which a geomembrane (GM). The success of these systems depends mainly on the GM performance, which acts as the primary barrier to contaminants migration. GM performance is conditioned by the presence of holes, which represent preferential pathways for leachate migration. An equipment was developed to detect holes in geomembranes. It is based on the geophysical resistivity method and aims to overcome the main disadvantages of the existing methods for GM holes detection, mainly time spent to perform the tests and the associated high costs. Several prototypes were already developed and were tested at small scale in laboratory. The final version, which is the model for the equipment under construction, was already successfully tested at laboratory small scale pilot plant and in a large pilot plant at Laboratório Nacional de Engenharia Civil, I.P. (LNEC) campus. This paper presents the prototypes development and results so far obtained.

Near Surface Geophysics, 2010

Porosity and degree of saturation-or the water content-are important parameters for hydrogeologic... more Porosity and degree of saturation-or the water content-are important parameters for hydrogeological, geotechnical and environmental studies. Geophysical methods, especially the resistivity method, are routinely employed to study the spatial variations of these parameters. Resistivity is highly influenced by the presence of water in pore spaces and hence is well suited for studying the presence of fluids on a site and its saturation condition. However, the non-uniqueness of the solution of resistivity models has led to the joint use of more than one geophysical method in order to reach more accurate geophysical models. In this research, we combined resistivity and seismic refraction profiles. The integration of these methods was particularly aimed to obtain 2D sections for estimating the porosity, water saturation and volumetric water content rather than to obtain a better geophysical solution. Independently inverted resistivity and P-wave refraction sections are the input data to an iterative analysis process using simulated annealing. Empirical equations taken from the literature are used to relate both the seismic velocity and the electrical resistivity with porosity and water saturation. Several parameters, such as the resistivity of water and clay; the velocity of water, clay, air and matrix; clay percentage and Archie's parameters remain constant throughout the process. The values considered for each parameter are derive from both the literature and laboratory measurements. Resistivity and seismic refraction profiles were performed on a site located within the LNEC campus. At this site, field measurements of void ratio and volumetric water content were performed at different depths. Soil samples were also collected at three different depths in order to perform laboratory measurements of these parameters and to determine soil composition. The laboratory results were compared with the 2D sections of each parameter. The proposed approach was also applied to two other locations with different and well characterized geology. These tests also allowed us to characterize the dependency of the clay content on the resistivity. This research has potential fields of application in environmental studies, in particular, the determination of probable pathways of pollutants; in hydrological investigations, where it can be useful to transport of nutrients studies; and in geotechnical studies, where, for example, it will be able to give a continuous image of the saturation degree of an embankment. ties and its subsurface structure, i.e., it reduces the non-uniqueness of the solution. This has led to the joint application of different techniques in geophysical prospecting. The joint inversion of different geophysical data usually needs a common parameter. For resistivity and seismic velocity, there are two ways to perform the joint inversion: by the petrophysical approach, in which both the porosity and the water saturation are the connecting link (e.g., Wempe 2000; Berryman et al. 2002), or by the structural approach, in which the pattern of the variation in properties is used as a common constraint (e.g., Haber and Oldenburg 1997), Gallardo and Meju (2003), de Nardis et al.

Journal of Applied Geophysics, 2004

... of a low resistivity fluid, the most obvious candidate being waste leachate diluted by ground... more ... of a low resistivity fluid, the most obvious candidate being waste leachate diluted by groundwater. ... Outcrop conditions preclude the geological detection of deep lying horizontal fracture zones. ... In any case, the spread of the leachate contamination is limited downward to around ...

International Journal of Environment and Waste Management, 2009

The evaluation of vibrations induced to build structures is one of the main concerns when dealing... more The evaluation of vibrations induced to build structures is one of the main concerns when dealing with blast works. EDP, the main Portuguese producer of electricity is presently incrementing energy production in some old hydropower dams by installing new production plants. The need for not disrupting production during the upgrading works causes some concerns related with vibrations induced to the production engines. Vibration estimation was performed in two of these dams, constructed in a granite environment, by performing controlled blasts. For each dam site, some vibration transmissivity laws were developed with the fitting process.

The presence of high vulnerable karstic systems in areas of intense human activities often result... more The presence of high vulnerable karstic systems in areas of intense human activities often results in the degradation of existing groundwater quality status. The water quality (WQ) protection and improvement, as required by the WFD (Water Framework Directive), depends on a correct prioritisation of the most relevant impact pollution sources to be identified within complex multi-stressor conditions. This paper presents a methodology that combines the use of hydrogeology, WQ and quantity data, and geophysical methods to access the human activities' impacts upon the water cycle, focusing on the WQ of a karstic system. The procedure was applied to a section of the Portuguese karstic Querença-Silves aquifer, under FCT PROWATERMAN project PTDC/AAC-AMB. During this study an interpretation of the possible interconnections between pollutant sources, their pathways and local surface-groundwater connections was analysed, based on data obtained from field campaigns. As a result of this stud...

Environ. Process., 2014

The presence of highly vulnerable karstic systems in areas of intense human activities often resu... more The presence of highly vulnerable karstic systems in areas of intense human activities often results in the degradation of existing surface-and groundwater quality status. Water quality protection and improvement, as required by the Water Framework Directive (WFD), depends on correct identification and prioritisation of the most relevant pollution sources within complex multi-stressor conditions. This paper presents a methodology that combines the use of hydrogeology, water quality and quantity data, and electrical resistivity tomography methods to access different anthropogenic impacts upon the water cycle, focusing on the water quality of a section of the Portuguese karstic Querença-Silves aquifer. During this study an interpretation of the possible interconnections between pollutant sources, their pathways and local surface-groundwater connections was made, based on data obtained from field campaigns. As a result of this study, the areas with more interconnection between surfaceand groundwater were identified, namely the influent sites from the local stream into the aquifer. The impact of the diffuse pollution sources was verified at the monitoring points, especially those located downstream of large farming plots. Pollution in this karst aquifer results from seepage through agricultural areas and infiltration at the influent points of the stream. This aspect of stream influence upon the aquifer means that pollution sources located upstream of the area of the aquifer (e.g., a WWTP-Wastewater Treatment Plant) can also contribute to the aquifer pollution.