Increased riverbed erosion could recently be observed in close vicinity of hydrotechnical constructions in many lowland rivers. The immediate effect of erosion in this case is a very significant reduction of the riverbed level over a considerable distance, downstream of large reservoir dams. This process is influenced simultaneously by both hydraulics of river flow and geotechnical properties of soil eroded. The paper presents an analysis of parametric changes in the level of river bottom and grain size of bed material, and the relative density in the context of changes in hydrological conditions and diversity of engineering-geological conditions. As the result, a multiparametric model of erosional potential of riverbed sediments has been proposed, which can significantly help in proper planning of locations and construction of correction thresholds under given hydraulic conditions of the river.
The river erosion is a complex process, the dynamics of which is very difficult to predict. Its intensity largely depends on hydraulic conditions of the river channel. However, it is also thought that natural resistance of the subsoil has a great influence on the scale of the erosion process. Predicting the effects of this process is extremely important in the case of constructing a piling structure (for example, artificial reservoirs). The partition of the river channel causes significant lowering of the river channel bed downstream the dam which threatens the stability of hydro technical and engineering (bridges) buildings. To stop this unwanted phenomenon, stabilizing thresholds are built. However, random location of thresholds significantly reduces their effectiveness. Therefore, taking under consideration natural geotechnical conditions of the subsoil appears to be extremely important. In the light of the current development of in-situ tests in geotechnics, an attempt to use results from these tests to predict the bed erosion rate was made. The analysis includes results from CPTU and DPL tests, which were carried out in the Warta River valley downstream the Jeziorsko reservoir. In the paper, the general diagrams for the procedure of obtaining and processing the data are shown. As a result, the author presents two multidimensional bed erosion rate models built based on hydraulic data and results from CPTU or DPL tests. These models allow taking more effective actions, leading to the neutralization of the effects of the intensive bed erosion process.
The paper presents results of geotechnical and geological investigation on flood plain of the Warta River, below the Jeziorsko reservoir. It is the section of the river, where the intensive erosion process of the river bed occurs. To stop this process thresholds are built. Their efficiency depends of ground conditions, especially spatial variability of geotechnical parameters. To describe the subsoil cone penetration tests were carried out. Subsequently Authors used statistical techniques to analyze variations of geotechnical parameters. Most of all, k-means method was applied. This well known cluster analysis is one of analysis which makes dividing subsoil into relatively homogeneous layers in different part of the river valley possible. However, Authors observed that in case of river alluvial 20% of variation of parameters values in layer is necessary to accept.
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W projektowanych obecnie budynkach bardzo często zachodzi konieczność lokalizacji dużych, wolnych od podpór, przestrzeni w dolnych kondygnacjach przy zupełnie odmiennym układzie konstrukcyjnym wyższych kondygnacji. W realizowanym projekcie budynku hotelowego autorzy pracy zaproponowali sprężony układ konstrukcyjny zbudowany z dwóch stropów oraz ścian żelbetowych jako środników, otrzymując ustrój podobny do stosowanych w mostownictwie. W pracy przedstawiono założenia konstrukcyjne, omówiono napotkane problemy, przedstawiono przyjęte parametry projektowe i wyniki analizy statyczno-wytrzymałościowej wybranych elementów ustroju nośnego. Na podstawie otrzymanych wyników i doświadczeń z projektowania wysnuto stosowne wnioski.
EN
Very often is necessary to use large spaces without supports in low floors in designed building where the construction system of the higher levels is completely different. In realized design for hotel building the authors of this paper have proposed prestressed structure made up two slabs and concrete walls as a I-beam web. It was formed the structure similar to box-section bridge beam. In this paper are presented and discussed the designing assumptions, parameters, the static and strength analysis results and the structure detailing. Based on the obtained results and experience from design process the conclusions was drawn.
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Beton siarkowy powstaje przez zmieszanie gorącego kruszywa ze zmodyfikowanym spoiwem siarkowym i wypełniaczem. Beton siarkowy jest układany tak jak beton cementowy, może być również zbrojony. Beton siarkowy twardnieje w ciągu kilku minut. Badania próbnego odcinka nawierzchni lotniskowej potwierdziły jego dobre parametry techniczne.
EN
Sulphur concrete is made by mixing of hot aggregate with modified sulphur binder and filler. Sulphur concrete is laid in the same way as cement concrete - it may be strengthened as well. Sulphur concrete hardens in few minutes. Tests on trial section of airport pavement confirmed its good technical parameters.
W niniejszej pracy przedstawiono informacje na temat technologii wykonywania nawierzchni z betonu siarkowego (BS), a także rezultaty własnych badań własności mechanicznych betonu siarkowego oraz wyniki badań płyty z BS o wymiarach 0,16x1,0x3,6 m sprężonej dwoma cięgnami bezprzyczepnościowymi 7 średnica 5 mm.
EN
In the paper there are presented some information dealing with preparation of subbase or surface to receive sulfur concrete, batching, transporting placing and finishing. Additionally the mechanical properties of sulfur concrete resulted of own investigations: compressive strength, tensile strength, modulus of elasticity in compression and sulfur concrete joint capacity in direct tension are also given. Moreover the results of experimental investigations carried out on prestressed sulfur concrete slab 1,0 x 3,6 x 0,16 with two unbonded 7 diameter 5 mm type are summarized.
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