Land subsidence phenomena caused by the overexploitation of the aquifers require the holistic knowledge of the geological, tectonic, hydrogeological and especially the geotechnical conditions of the affected sites in ...Land subsidence phenomena caused by the overexploitation of the aquifers require the holistic knowledge of the geological, tectonic, hydrogeological and especially the geotechnical conditions of the affected sites in order to be mitigated. The current paper focuses on the study of the phenomena taking place at the Amyntaio sub-basin, northern Greece, hosting the homonymous open pit coal mine,operating there the last two decades. The mining as well as the rising agriculture activities have led to a significant drawdown of the ground water level triggering extensive ground subsidence phenomena,causing damages at the nearby villages, infrastructure and farmlands. The production and evaluation of engineering geological–geotechnical maps as well as of thematic tectonic and hydrogeological maps proved that the knowledge of this data is crucial for the interpretation of the land subsidence mechanism and the spatial distribution of its effects.展开更多
Flysch formations are generally characterised by evident heterogeneity in the presence of low strength and tectonically disturbed structures. The complexity of these geological materials demands a more specialized geo...Flysch formations are generally characterised by evident heterogeneity in the presence of low strength and tectonically disturbed structures. The complexity of these geological materials demands a more specialized geoengineering characterisation. In this regard, the paper tries to discuss the standardization of the engineering geological characteristics, the assessment of the behaviour in underground excava- tions, and the instructions-guidelines for the primary support measures for flysch layer qualitatively. In order to investigate the properties of flysch rock mass, 12 tunnels of Egnatia Highway, constructed in Northern Greece, were examined considering the data obtained from the design and construction records. Flysch formations are classified thereafter in 11 rock mass types （I-XI）, according to the siltstone -sandstone proportion and their tectonic disturbance. A special geological strength index （GSI） chart for heterogeneous rock masses is used and a range of geotechnical parameters for every flysch type is presented. Standardization tunnel behaviour for every rock mass type of flysch is also presented, based on its site-specific geotechnical characteristics such as structure, intact rock strength, persistence and complexity of discontinuities. Flysch, depending on its types, can be stable even under noticeable overburden depth, and exhibit wedge sliding and wider chimney type failures or cause serious deformation even under thin cover. Squeezing can be observed under high overburden depth. The magnitude of squeezing and tunnel support requirements are also discussed for various flysch rock mass types under different overburdens. Detailed principles and guidelines for selecting immediate support mea- sures are proposed based on the principal tunnel behaviour mode and the experiences obtained from these 12 tunnels. Finally, the cost for tunnel support from these experiences is also presented.展开更多
Oasis of the Rheris is located in the South-East of Morocco in the province of Errachidia, in the region of Draa-Tafilalt. This zone of study contains in its administrative unit the municipality of Goulmima, and two r...Oasis of the Rheris is located in the South-East of Morocco in the province of Errachidia, in the region of Draa-Tafilalt. This zone of study contains in its administrative unit the municipality of Goulmima, and two rural communes: Gheris El Ouloui and Gheris Essoufli. The cretaceous basin of Gheris constitutes of the principal geomorphological entities is limited by the carbonated Jurassic High-Atlas in Tadighoust in north and west. In the south, the Anti-Atlas chain of Mellab and Tinjdad is dominated by a Precambrian base which supports with its back a thick cover of the Paleozoic. And in the center there is Rheris Oasis which characterizes this bioclimatic zone. This oasis looks like an island in the saharan desert. Finally, Hammada de Meski is located in the east. In the tourist literature of Morocco, it mentions the gravitational landscapes in the south of Morocco, of which are geomorphosites of Goulmima that offer superb landscapes. From my point of view, the primary reason behind this research task is to promote geo-eco-tourism for sustainable development of this area. Several tourists cross the zone of study, especially Amellagou-Tinjdad circuit because they are attracted much when they arrive at the beautiful landscape of Rheris, such as geomorphlogical landscape (Tifounassine: full of fresh water). There are many other sources like Tamda N’mssoud, Boukhazm and Asdram of a distance from important observation which offers a beautiful vision on the synclinorium infracenomanian. According to Panizza (2001), the geomorphosites are forms of the relief which have acquired a scientific, cultural and historical, aesthetic, didactic and/or socio-economic value because of their perception. The cartography of the geomorphosites fundamentally aims at giving to the users an immediate perception of the space distribution and representation of the forms of the relief [1]. Today, the use of the Geographical Information Systems has acquired an important growing because of the possibilities of update and interaction with the user with a view to natural regional planning. The digital models of ground (MNT), extracted from the satellite pictures offer valuable help for the analysis and the detailed cartography of the reliefs. The GIS applied to the geographical zone of Goulmima led to the construction and the reading of the results produced by several cards sets of themes.展开更多
Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to b...Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.展开更多
文摘Land subsidence phenomena caused by the overexploitation of the aquifers require the holistic knowledge of the geological, tectonic, hydrogeological and especially the geotechnical conditions of the affected sites in order to be mitigated. The current paper focuses on the study of the phenomena taking place at the Amyntaio sub-basin, northern Greece, hosting the homonymous open pit coal mine,operating there the last two decades. The mining as well as the rising agriculture activities have led to a significant drawdown of the ground water level triggering extensive ground subsidence phenomena,causing damages at the nearby villages, infrastructure and farmlands. The production and evaluation of engineering geological–geotechnical maps as well as of thematic tectonic and hydrogeological maps proved that the knowledge of this data is crucial for the interpretation of the land subsidence mechanism and the spatial distribution of its effects.
文摘Flysch formations are generally characterised by evident heterogeneity in the presence of low strength and tectonically disturbed structures. The complexity of these geological materials demands a more specialized geoengineering characterisation. In this regard, the paper tries to discuss the standardization of the engineering geological characteristics, the assessment of the behaviour in underground excava- tions, and the instructions-guidelines for the primary support measures for flysch layer qualitatively. In order to investigate the properties of flysch rock mass, 12 tunnels of Egnatia Highway, constructed in Northern Greece, were examined considering the data obtained from the design and construction records. Flysch formations are classified thereafter in 11 rock mass types （I-XI）, according to the siltstone -sandstone proportion and their tectonic disturbance. A special geological strength index （GSI） chart for heterogeneous rock masses is used and a range of geotechnical parameters for every flysch type is presented. Standardization tunnel behaviour for every rock mass type of flysch is also presented, based on its site-specific geotechnical characteristics such as structure, intact rock strength, persistence and complexity of discontinuities. Flysch, depending on its types, can be stable even under noticeable overburden depth, and exhibit wedge sliding and wider chimney type failures or cause serious deformation even under thin cover. Squeezing can be observed under high overburden depth. The magnitude of squeezing and tunnel support requirements are also discussed for various flysch rock mass types under different overburdens. Detailed principles and guidelines for selecting immediate support mea- sures are proposed based on the principal tunnel behaviour mode and the experiences obtained from these 12 tunnels. Finally, the cost for tunnel support from these experiences is also presented.
文摘Oasis of the Rheris is located in the South-East of Morocco in the province of Errachidia, in the region of Draa-Tafilalt. This zone of study contains in its administrative unit the municipality of Goulmima, and two rural communes: Gheris El Ouloui and Gheris Essoufli. The cretaceous basin of Gheris constitutes of the principal geomorphological entities is limited by the carbonated Jurassic High-Atlas in Tadighoust in north and west. In the south, the Anti-Atlas chain of Mellab and Tinjdad is dominated by a Precambrian base which supports with its back a thick cover of the Paleozoic. And in the center there is Rheris Oasis which characterizes this bioclimatic zone. This oasis looks like an island in the saharan desert. Finally, Hammada de Meski is located in the east. In the tourist literature of Morocco, it mentions the gravitational landscapes in the south of Morocco, of which are geomorphosites of Goulmima that offer superb landscapes. From my point of view, the primary reason behind this research task is to promote geo-eco-tourism for sustainable development of this area. Several tourists cross the zone of study, especially Amellagou-Tinjdad circuit because they are attracted much when they arrive at the beautiful landscape of Rheris, such as geomorphlogical landscape (Tifounassine: full of fresh water). There are many other sources like Tamda N’mssoud, Boukhazm and Asdram of a distance from important observation which offers a beautiful vision on the synclinorium infracenomanian. According to Panizza (2001), the geomorphosites are forms of the relief which have acquired a scientific, cultural and historical, aesthetic, didactic and/or socio-economic value because of their perception. The cartography of the geomorphosites fundamentally aims at giving to the users an immediate perception of the space distribution and representation of the forms of the relief [1]. Today, the use of the Geographical Information Systems has acquired an important growing because of the possibilities of update and interaction with the user with a view to natural regional planning. The digital models of ground (MNT), extracted from the satellite pictures offer valuable help for the analysis and the detailed cartography of the reliefs. The GIS applied to the geographical zone of Goulmima led to the construction and the reading of the results produced by several cards sets of themes.
文摘Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.
