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Collaborating Authors
Carboniferous
Selected Geological Factors Impacting Effects of Induced Seismicity On Surface In Conditions of Ostrava-Karvina Coalfield In the Czech Republic
Holecko, Josef (Department of Geomechanics and Geophysics, OKD, DPB, a.s. Paskov) | Konicek, Petr (Department of Geomechanics and Geophysics, OKD, DPB, a.s. Paskov)
ABSTRACT Underground exploitation of hard coal deposit in Ostrava-Karvina Coalfield which is the Czech part of Upper Silesian Coal Basin is accompanied by induced seismicity. This seismicity can be manifested negatively by rock bursts occurrence in underground workings and/or by vibration on the surface. The magnitude of surface vibration can be influenced by several factors. The basic factors are geological properties of rock mass – the thickness and the quality of overburden of Carboniferous strata and the level of underground water. In the paper authors analyse possible impact of these factors on surface vibration in conditions of Ostrava-Karvina Coalfield. The influence of rock burst and seismicity on surface is being observed by a network of standard underground and surface seismic stations and interpreted since late 1990's. In previous few years the particle velocity was measured by mobile seismic stations on Earth's surface in selected localities. These values were compared with those interpreted from the standard seismic network data. The analyses of geological properties, in the sites where the mobile seismic stations were situated and the assessment of differences between measured and interpreted velocities, give an idea how the geological properties influence the magnitude of particle velocity on the surface structures. The results are also discussed in the paper. 1 INTRODUCTION Annually several tens thousands of minor induced seismic events are recorded in Karvina part of Ostrava-Karvina Coalfield (OKR) in Czech Republic. OKR is the southern part of the Upper Silesian Coal Basin (see fig. 1). Energetically significant major induced seismic events are only few tens. Some of these events are accompanied by earth tremor. This fact is affected by several factors. Among basic factors the following ones can be included:The quantity of released seismic energy and the location of seismic focal area activity (epicenter), The physical and mechanical properties of rock mass environment between the seismic focal area and the place of seismic performance on surface, The properties of the strata under the surface (ground water level, geological structure, tectonics etc.). The impacts of induced seismicity on the surface are observed more or less in inhabited regions. 2 NATURAL CONDITIONS Carboniferous rock formation in Karvina part of OKR is created by Karvina and Ostrava strata (see figs 3 and 4). The coal seams of Karvina strata are recently massively exploited. Karvina strata represent a continental coal-bearing molasa in OKR (middle and upper Namur, Westphal A). In contrast to lithological nature of western part of OKR the sedimentary cycles are conspicuously longer and moreover sandstones are prevailing. Compression strength values of such rocks are distinctly higher ones than those of mudstones and siltstones. In thicker banks of rigid rock components then higher stress concentrations occur than in other parts of rock massif. This condition has been manifested most conspicuously in Saddle beds, which are basal part of Karvina series of strata. The Saddle beds are featured by several tens of meters thick banks of rigid rocks (sandstones, sandy siltstones and conglomerates (Dopita et al. 1997).
- Europe > Czechia > Moravian-Silesian Region > Ostrava (1.00)
- Europe > Belgium > Wallonia > Namur Province > Namur (0.24)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (1.00)
- Europe > Poland > Upper Silesian Basin (0.99)
- Europe > United Kingdom > England > London Basin (0.91)
The Baixo Alentejo (Portugal) Flysch Rocks: Physical Properties And Correlations
Pinho, A.B. (Minerais Industriais e Argilas Research Centre, Department of Geosciences, University of Evora ) | Duarte, I.M.R. (Minerais Industriais e Argilas Research Centre, Department of Geosciences, University of Evora ) | Rodrigues-Carvalho, J.A. (Centro de Estudos Geologicos Research Centre, Department of Earth Sciences, New University of Lisbon)
ABSTRACT This paper is intended as a contribution to the knowledge of the mineralogical and physical characteristics as well as their variations with the state of weathering for the rock materials belonging to the Baixo Alentejo Flysch Group, in the south of Portugal. The study was made by using both shales and greywackes that constitute these flysch-type deposits. Samples of these two rock materials, with different states of weathering, were collected during a planned fieldwork survey.A laboratory tests programme was then carried out, which included mineralogical analysis by X-ray diffraction and physical tests namely dry density, porosity, quick absorption, slake-durability and methylene blue adsorption tests. Considerations are drawn in the paper about the results of the study and some correlations are established between the different physical parameter values and also between some of these and the mineralogical characteristics of the shales and greywackes. 1 INTRODUCTION The establishment of correlations between different parameters within the scope of the study of rock materials seems to be very important task because it emphasizes the tendencies on the behaviour of the rock materials and allows the assessment of the most suitable parameters for their characterization. 2 GEOLOGICAL SETTING The rock material selected for this study belongs to the Baixo Alentejo Flysch Group (BAF), a stratigraphic unit with an approximate area of 8000 Km2, which extends across more than a half of the South Portuguese Zone depositional area (Figure 1). This group comprises gravity flow sediments that form a continuous turbiditic succession (Oliveira, 1990). Sedimentological and stratigraphic characteristics indicate three basin-wide formations: the Mertola Formation of late Visean age, the Mira Formation of latestVisean to Namurian age and the Brejeira Formation of mid Namurian to earlyWestphalian age (Oliveira, Horn & Paproth, 1979; Oliveira, 1983). These lithostratigraphic units of the BAF are constituted, as a rule, by thick sequences of turbidites where greywackes beds, usually of few tens of centimetres thick but sometimes reaching some metres thick, with lenses or pockets of fine grained conglomerates, are intercalated with thin, black / dark-grey shale beds. 3 TESTING PROGRAMME AND RESULTS A set of samples of shale and greywacke which represent different states of weathering, belonging to the Mertola, Mira and Brejeira formations of BAF, was collected in excavation slopes of some main roads and from exploratory boreholes, in the Alentejo region in the South of Portugal (Figure 1). The samples are fully described in Pinho (2003). The mineralogical composition of shales and greywackes is similar, with the relative proportion of the occurring minerals varying. Both rock types are formed by quartz, feldspar (mainly calcium feldspars), micas and clay minerals, particularly kaolinite, illite and chlorite. In some samples, carbonates (mainly calcite, and siderite), pyrite and haematite occur in smaller percentages. The greywackes are formed mainly by quartz and calcium feldspar that were involved by a cemented material mainly composed of phyllosilicates, but also of calcite, siderite and pyrite.
- Phanerozoic > Paleozoic > Carboniferous > Mississippian > Middle Mississippian > Visean (0.54)
- Phanerozoic > Paleozoic > Carboniferous > Pennsylvanian > Lower Pennsylvanian > Bashkirian (0.34)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral > Silicate > Tectosilicate (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Geological Subdiscipline (1.00)
- Europe > United Kingdom > England > London Basin (0.91)
- Europe > Greece (0.91)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (0.69)
ABSTRACT A site investigation is needed prior to any civil engineering construction. The results of this site investigation must lead to recognition of problems related to geology. If the problems related to the geology-structure interaction cannot be handled economically, the structure has to be relocated into more suitable terrains. In some cases, as for line infrastructures (e. g. highways, railroads etc.) this relocation is not always possible. In these cases the problems related to the implementation of the structure into the geology have to be overcome. In this light, karstified areas belong to the most difficult engineering terrains. Although the presence of karst in a certain region can be identified during a site investigation, the exact location of karst voids cannot be predicted with a precision accurate enough for construction. In this contribution, an inventory is made of the possible presence of karst in Belgium. Then 2 case studies are presented in which the particularities of karst of different age (Palaeokarst, Mesozoic karst and Caenozoic karst) are presented. 1 WHERE CAN WE FIND KARST IN BELGIUM One method to analyse the extent of karst in a region consists in mapping outcrops of the lithologies prone to dissolution. In Belgium the areas that could be affected by karst are restricted predominantly toWallonia. In Wallonia the karst is restricted predominantly to Palaeozoic rocks1. In these Palaeozoic rocks the karst is restricted to those that consist of limestone and dolomite, most karst can be found in the limestone (Ek 1996). The occurrence of the outcrops2 of these formations is shown in figure 1. Our contribution will, on the basis of the karst features in Belgium, discuss only the carbonate karst. Brussels the largest city in Belgium, Antwerp the largest city in Flanders and Liège the largest city inWallonia: in fact 94% of the population of Belgium is fenced in by the karst belt, shown in figure 2, which starts in the west near Tournai and continues via Mons and Charleroi to the German border, then it turns north between Liège and the Netherlands border but here in the subsurface. If one wants to connect Belgian cities to Germany or France one has unavoidably to pass this Belgian karst belt. 2 KARST FORMED DURING THREE DIFFERENT GEOLOGICAL ERAS Karst encountered in Belgium was formed either during the Palaeozoic (Visean), Mesozoic (Lias) or during the Caenozoic. 3 CASE I: TUNNEL DE SOUMAGNE Introduction A major achievement of the Belgian railway was the recent construction of a high-speed railroad from Brussels via Liège and Aachen to Cologne. The track Brussels – Liège has been inaugurated 2003. Thereafter construction focused on the section Liège – Aachen. To be able to maintain a high travel velocity the path of the former, rather curved railroad, was not be followed. Unavoidably a tunnel needed to be constructed to pass through some hills on theway from Liège to the plateau de Herve. This tunnel is the Soumagne tunnel (the breakthrough occurred in October 2004).
- Phanerozoic > Paleozoic > Carboniferous > Pennsylvanian > Lower Pennsylvanian > Bashkirian (0.68)
- Phanerozoic > Paleozoic > Carboniferous > Mississippian (0.46)
ABSTRACT Big quarries are mined out in the Tournai's region (Belgium) for cement or crushed raw materials production. The development of this industrial activity is due to famous outcrops of carboniferous limestone in the region. The rock masses in the area are characterised by three sets of discontinuities among which two have a near vertical dipping; and these sets are intersected a time to time by some typical faults. It is generally recognised that, when subjected to the effect of percolating water, the limestone undergoes a weathering leading to very poor material on the mechanical point of view. Such a material cannot be used as crushed rock. When designing the rock blast, the mining engineer has to plan and drive the operations in order to decide about the most suitable destination for the mined out material, i.e. crusher of waste dump. A particular method has been developed in this paper to assess continuously the quality of the rock being drilled for blast holes. This uses the drilling logs (i.e. weight on bit, rate of penetration, and rotation torque) to evaluate the strength of the rock mass.A mechanical "energy index" that can be related to the destruction specific energy is defined.A correlation is then built with the GSI (Geological Strength Index) as described by Hoek and Brown (1997). The working method involves the definition of the GSI per zone and a specific treatment to assess the magnitude of the corresponding energy index. This can be used to update the geological map of a quarry based mainly on the directions of natural fractures. 1 INTRODUCTION The "Societe des Carrières du Tournaisis (SCT)" is mining the "Carrière du Milieu", a quarry in Gaurain-Ramecroix, a village close to the Tournai city, Belgium. This quarry supplies two big companies with crushed materials (Holcim) and cement+crushed materials (Italcimenti) for an overall planed production of 11 millions tons per year. While the cement production relies on the chemical quality of the limestone, the production of crushed rocks requires good mechanical properties. The Tournai's limestone deposit is intersected by a series a sub vertical joints that divide the body into different blocks, and hence, lead to the typical cave weathering phenomenon. The mining operations in the quarry show that the extent of weathering, mainly in the shallowbenches, can lead to a recovering of less than 40% of the rocks, the remaining material is dumped in the waste backfilling area of the western depleted part of the quarry. It is therefore of some importance to develop a prediction tool that can rapidly allowthe production engineer to decide about the destination of the removed block. 2 GEOLOGICAL DESCRIPTION OF THE SITE UNDER STUDY TheTournai's limestone outcrop belongs to the Carboniferous formations of the northern border of Namur's Synclinorium (Belgium). This is a strip lying from eastern Namur to western Lille in France.
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics (0.49)
ABSTRACT The Jietai Temple landslide threatened the safety of the Jietai Temple, an ancient temple with a history of more than 1400 years. In the paper, the landslide is briefly described and the stress is placed on its control. In order to prevent the further development of the landslide, the two phases of control were performed: emergency control and temple-protecting control. In the two phases of control, 35 anti-slide piles and 35000m long anchor cables was used. The practice proved that pre-stressed anchor anti-slide piles are suitable for controlling such landslides as the Jietai Temple. Some new technical means such as a multi-anchoring point anti-slide pile were developed and adopted in treating of difficult problems. 1 INTRODUCTION The Jietai Temple is one of the national key cultural relic preservation units in china. It is located on the north slope of the Ma'anshan Mountain of the Mentouggou District of Beijing, 35 km away from the city proper. It was constructed during the Sui Dynasty and has a history of more than 1400 years. Unfortunately, the temple is on a landslide. The landslide has been named the Jietai Temple landslide. Therefore, the Jietai Temple has always been faced with its threats. In the paper, the landslide is briefly described, but the stress is placed on the controlling measures that were adopted for it. 2 JIETAI TEMPLE LANDSLIDE Figure 1 is a sketch section of the Jietai Temple landslide. The landslide is about 1200m long and, from east to west, about 450mwide. The height difference from the front to the tail end is about 230m and the average thickness is about 47 m, with the volume being about 9000000m3. The east and west sides of the landslide are embraced by natural gullies and hollows. That is, except for the south side, the landslide has three air faces. The main strata at the Jietai Temple are the Carboniferous system (C), the Permian system (P) and the Quaternary system (Q). The Jietai Temple landslide is composed of Carboniferous strata. The upper part of the landslide include gray and dark gray fine sandstone, siltstone, shale, and 2 or 3 interbeds of clay and coal.The lower part is gray andwhite gray gravel-bearing coarse quartz sandstone, of which the heavily weathered is brown-yellow. The slide zone is a layer of black clay, which is relativelywater-resisting andwould become soft after water saturation. The overlying is brown-yellow sandstone, which is hydrous. The underlying is mid-Carboniferous sandstone, which is dark, compact and hard, containing more pyrite and quartz. The Carboniferous and Permian strata dip north and have dip angles of 30∼45°, steeper upwards. They constitute the north limb of the Ma'anshan Mountain anticline. In fact, the hill ridge which the Jietai Temple landslide is located on is a consequent slope. Because of the intersection of 9 east-west striking faults and 3 north-south striking faults, the hill ridge looks much fractured.
- Phanerozoic > Paleozoic > Carboniferous (0.88)
- Phanerozoic > Paleozoic > Permian (0.54)
- Geology > Mineral > Silicate (0.95)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.86)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.54)