The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
Rafael Cerqueira Silva - One of the best experts on this subject based on the ideXlab platform.
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Behavior of a colluvial slope located in Southeastern Brazil
Landslides, 2018Co-Authors: Mauricio Ehrlich, Douglas Pereira Costa, Rafael Cerqueira SilvaAbstract:Colluvial deposits are commonly found throughout the Serra do Mar escarpment in Brazil. This article discusses predisposing geotechnical and geological factors related to the movement of a colluvium deposit located at km 29 of the Brazilian Federal Highway 116, Rio de Janeiro/RJ (BR-116/RJ). During the highway construction in mid-1976, an excavation of the toe of the slope was implemented, exacerbating preexisting movement. In order to understand the behavior of this deposit, field investigations, monitoring, and laboratory tests, as well as theoretical analyses were carried out. A subsoil survey in the area indicated the presence of a colluvium-filled paleo-thalweg. The site is located in a region with a specific geomorphology that favors significant sources of recharge to groundwater. The highly foliated rock has persistent parallel fractures, with a dip favorable to the groundwater flow in the direction of the slope. Statistical analyses were performed and good correlations were observed for rainfall, movements, groundwater table (GWT) levels, piezometer readings, and the discharge from deep horizontal drains (DHDs). The installation of the DHDs led to a GWT draw-down of 15 m, as well as reductions in movement and Artesian Pressure. The drains that presented the best performance were those installed in the colluvium-filled paleo-thalweg. Nevertheless, the present number of DHDs installed is not sufficient to permanently lower the GWT and stop the creep movement in the slope which was reactivated during a period of intense rainfall. Stability analysis indicates that a proper slope stability condition may be achieved by reducing the GWT level.
Hiroomi Nakazato - One of the best experts on this subject based on the ideXlab platform.
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estimation of pore Pressure in disturbed mudstone from natural water content with special reference to landslide and squeezing swelling tunnel
Soils and Foundations, 1996Co-Authors: Ryoki Nakano, Hideyoshi Shimizu, Shinichi Nishimura, Hiroomi NakazatoAbstract:ABSTRACT To elucidate the engineering significance of natural water content of mudstone disturbed into clay from the view point of Critical State Soil Mechanics, CD triaxial test (with top and bottom drainage only) and CD direct shear test were carried out and the unique relationship between log qmax (or log τmax) and w and that between w and logp' (or log σv′) were obtained. Comparing the experimental results thus obtained, p' was found to be nearly equal to σv′ in fully softened shear zone. Thus, if wn at the depth of h is known, the effective confining stress p' at that depth can be known. Therefore the pore Pressure acting at that depth can be calculated as u = γt ·h–p'. Two example case histories, Mizunashi landslide and Nabetachiyama tunnel in Neogene mudstone of Shiiya formation in Niigata Prefecture are presented. In the former, by measuring wn of boring core of 90 m, several number of fully softened shear zones were found to exist where Artesian Pressure was acting and, in the latter, in the section where tunneling was very difficult due to squeezing Pressure, wn of fault clay was found to correspond either to p' induced by the overburden weight or to p' decreased by the amount of methane gas Pressure.
Barbara Tomaszewska - One of the best experts on this subject based on the ideXlab platform.
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Using treated geothermal water to replenish network water losses in a district heating system
Polish Journal of Environmental Studies, 2020Co-Authors: Barbara Tomaszewska, Leszek PająkAbstract:This paper examines the use of geothermal water to replenish network water losses in the largest Polish geothermal heating system. The geothermal installation capacity (under Artesian conditions) is 670 m 3 /h. The total power of the geothermal water source is 15.4 MW, and it is assisted by peak load boilers. The total capacity of the heating plant is 80.5 MW, and energy output amounts to 324 TJ/year. The system serves ca. 1,500 customers and includes ca. 95 km of district heating distribution network (Fig. 2). Distribution network water losses amount to ca. 6,600 m 3 /year. The water used to replenish the losses is currently treated using ion exchange water softeners and vacuum degasifiers. It is suggested that the missing water be replaced with treated geothermal water; following treatment, this water must meet the requirements set forth in the water quality standards for heating systems (PN-85/C-04601 – Table 1). The treatment uses membrane processes within the framework of a double hybrid arrangement, including ultrafiltration and reverse osmosis. Artesian Pressure is used to a certain extent during treatment, which makes it possible to reduce the power required for the distribution pump, decreasing electrical power consumption. Thus, the requirements set forth in the standards have been met and the treated geothermal water can be used to replenish network water losses in the district heating system following pH adjustment and degassing.
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The Analysis of Geothermal Well Constructions Depending on Expected Pressure Conditions
Renewable Energy Sources: Engineering Technology Innovation, 2020Co-Authors: Anna Chmielowska, Barbara Tomaszewska, Anna SowiżdżałAbstract:Geothermal energy, the internal heat of the Earth, has a tremendous energetic potential. As a renewable source of energy, it is an excellent alternative to conventional raw materials in the context of acquiring thermal energy and generating electricity. It can be also intended for recreational and balneological purposes. However, the use of geothermal energy is possible mainly due to deep boreholes, which at the present stage of technology development, remain the only rational solution. Since the stage of wellbore drilling is the largest financial burden of any geothermal investment it is a matter of great importance to properly design a borehole. The expected operating conditions should be considered, among which the Pressure - Artesian or subArtesian, plays a crucial role. Also, the possibility of a justified adaptation of old explorative or abandoned petroleum wells for geothermal purposes is a preferable or even desirable solution of current years. Thus, the most important issues related to the construction of geothermal wells, in dependence on the expected Artesian or sub-Artesian Pressure, are discussed throughout the paper. The existing examples of reconstructed (Mszczonów IG-1), dedicated or suggested for reconstruction (Poręba Wielka IG-1, Wiśniowa-1) wells located in Poland are characterized.
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The Analysis of Geothermal Well Constructions Depending on Expected Pressure Conditions
Springer Proceedings in Energy, 2019Co-Authors: Anna Chmielowska, Barbara Tomaszewska, Anna SowiżdżałAbstract:Geothermal energy, the internal heat of the Earth, has a tremendous energetic potential. As a renewable source of energy, it is an excellent alternative to conventional raw materials in the context of acquiring thermal energy and generating electricity. It can be also intended for recreational and balneological purposes. However, the use of geothermal energy is possible mainly due to deep boreholes, which at the present stage of technology development, remain the only rational solution. Since the stage of wellbore drilling is the largest financial burden of any geothermal investment it is a matter of great importance to properly design a borehole. The expected operating conditions should be considered, among which the Pressure - Artesian or subArtesian, plays a crucial role. Also, the possibility of a justified adaptation of old explorative or abandoned petroleum wells for geothermal purposes is a preferable or even desirable solution of current years. Thus, the most important issues related to the construction of geothermal wells, in dependence on the expected Artesian or sub-Artesian Pressure, are discussed throughout the paper. The existing examples of reconstructed (Mszczonow IG-1), dedicated or suggested for reconstruction (Poreba Wielka IG-1, Wiśniowa-1) wells located in Poland are characterized.
Mauricio Ehrlich - One of the best experts on this subject based on the ideXlab platform.
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Behavior of a colluvial slope located in Southeastern Brazil
Landslides, 2018Co-Authors: Mauricio Ehrlich, Douglas Pereira Costa, Rafael Cerqueira SilvaAbstract:Colluvial deposits are commonly found throughout the Serra do Mar escarpment in Brazil. This article discusses predisposing geotechnical and geological factors related to the movement of a colluvium deposit located at km 29 of the Brazilian Federal Highway 116, Rio de Janeiro/RJ (BR-116/RJ). During the highway construction in mid-1976, an excavation of the toe of the slope was implemented, exacerbating preexisting movement. In order to understand the behavior of this deposit, field investigations, monitoring, and laboratory tests, as well as theoretical analyses were carried out. A subsoil survey in the area indicated the presence of a colluvium-filled paleo-thalweg. The site is located in a region with a specific geomorphology that favors significant sources of recharge to groundwater. The highly foliated rock has persistent parallel fractures, with a dip favorable to the groundwater flow in the direction of the slope. Statistical analyses were performed and good correlations were observed for rainfall, movements, groundwater table (GWT) levels, piezometer readings, and the discharge from deep horizontal drains (DHDs). The installation of the DHDs led to a GWT draw-down of 15 m, as well as reductions in movement and Artesian Pressure. The drains that presented the best performance were those installed in the colluvium-filled paleo-thalweg. Nevertheless, the present number of DHDs installed is not sufficient to permanently lower the GWT and stop the creep movement in the slope which was reactivated during a period of intense rainfall. Stability analysis indicates that a proper slope stability condition may be achieved by reducing the GWT level.
Ezzatollah Raeisi - One of the best experts on this subject based on the ideXlab platform.
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Potential leakage at the Khersan 3 Dam Site, Iran: a hydrogeological approach
Bulletin of Engineering Geology and the Environment, 2007Co-Authors: Hossain Karimi, Toraj Keshavarz, Zargham Mohammadi, Ezzatollah RaeisiAbstract:The paper discusses the investigations into the Khersan 3 Dam site in the Zagros Zone, southern Iran, where the Rig, Shorom and Laki Anticlines meet. The Asmari Limestone is the main aquifer system in the area of the dam site and its reservoir. Marly bands within the Lower Asmari Unit create three confined sub-aquifers under Artesian Pressure overlain by one unconfined sub-aquifer. The impounded water will be in direct contact with the Asmari Limestone hence leakage may occur through existing karst features. As the recharge zone of the Artesian sub-aquifers is higher than the normal water level in the reservoir, no direct leakage through the Artesian sub-aquifers is anticipated. However, when the water head in the unconfined sub-aquifer rises with the construction of the dam, leakage may occur and further karstification develop. L’article présente les travaux de reconnaissance réalisés sur le site du barrage de Khersan 3, dans la région du Zagros au sud de l’Iran, au niveau des anticlinaux de Rig, Shorom et Laki. La formation des calcaires d’Asmari est le principal système aquifère au niveau du site du barrage et de son réservoir. Des niveaux marneux dans la partie inférieure de l’unité d’Asmari sont à l’origine de trois nappes captives surmontées par une nappe libre. L’eau de la retenue sera en contact direct avec les calcaires d’Asmari et, de ce fait, des fuites pourront avoir lieu au travers du karst. Comme la zone de recharge des nappes captives est plus haute que le niveau normal du réservoir, on ne craint aucune fuite au travers des aquifères correspondants. Cependant, lorsque la charge hydraulique dans l’aquifère de la nappe libre augmentera avec la construction du barrage, des fuites pourront avoir lieu et la karstification pourra se développer.
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Potential leakage at the Khersan 3 Dam Site, Iran: a hydrogeological approach
Bulletin of Engineering Geology and the Environment, 2006Co-Authors: Hossain Karimi, Toraj Keshavarz, Zargham Mohammadi, Ezzatollah RaeisiAbstract:The paper discusses the investigations into the Khersan 3 Dam site in the Zagros Zone, southern Iran, where the Rig, Shorom and Laki Anticlines meet. The Asmari Limestone is the main aquifer system in the area of the dam site and its reservoir. Marly bands within the Lower Asmari Unit create three confined sub-aquifers under Artesian Pressure overlain by one unconfined sub-aquifer. The impounded water will be in direct contact with the Asmari Limestone hence leakage may occur through existing karst features. As the recharge zone of the Artesian sub-aquifers is higher than the normal water level in the reservoir, no direct leakage through the Artesian sub-aquifers is anticipated. However, when the water head in the unconfined sub-aquifer rises with the construction of the dam, leakage may occur and further karstification develop.
