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EN
The study deals with landslide threats in a low-relief region which exemplifies an area rarely perceived as prone to such geohazards. Actually, in the gently undulated landscape in the vicinity of Koronowo at the Brda River (South Pomeranian Lake District, northern Poland) intensified landsliding was observed in the recent years. The field mapping and examination of air photos showed that endangered terrains are fairly extensive and cannot be limited to initially identified slope failure incidences (hot-spots). The devised landslide susceptibility and hazard map is an outcome of predictive modelling using empirical likelihood ratio function (LR) with respect to seven evidential layers: elevation, slope angle, slope aspect, flow accumulation, surface deposits, depth to glacial raft, land cover as well as the landslide scars. The values of potential losses were calculated based on the mapped land-use categories and current market prices of estates and services. The final map, which resulted from combining landslide hazard with potential losses, shows damage propensity in a spatial scale of the town surroundings. It is meant as a supportive tool for decision-making with regard to allocating funds for stabilization measures or planning placement of new investments. On this background, stabilization solutions for selected sites are assessed in a cost-benefit context.
EN
A small-scale model experiment on the pull-out resistance of suction caissons is described. The pull-out force and suction developed within the caisson in the extraction process were recorded during the experiment. A simple breakout model, together with an elementary static formulae, is applied to predict the results obtained experimentally. There is a reasonably good agreement between the experimental results and predictions. An extensive discussion of the approach applied is included. The analysis presented in this paper is original, as it differs from other approaches mentioned in this paper, and leads to acceptable predictions. At the end, the results are also compared with another approach for predicting the capacity of suction caissons.
3
Content available remote Deformacja ściany oporowej z gruntu zbrojonego – teoria i eksperyment
PL
Podstawowe informacje o metodzie analizy odkształceń pionowej ściany oporowej z gruntu zbrojonego. Cel i zakres badań. Parametry gruntu i zbrojenia. Badania doświadczalne. Porównanie wyników teoretycznych i doświadczalnych.
EN
Methodology of the deformation of the reinforced soil retaining wall analysis. The aim and the scope of tests. Parameters of the soil and reinforcement. Experimental model tests. Comparison of theoretical and experimental results.
EN
In the recentyears intensified landslidingwas observed in the surroundings and in the town of Koronowo near Bydgoszcz. (Krajeñskie Lake District). The gently undulated moraine upland, a wide valley of the Brda river, its relatively steep valleysides and incised valleys of tributaries are morphologicfeatures related to modeling by North Polish Glaciation. Quaternary tills alternated with fluvioglacial sands and gravels are underalined by Miocene clay and mud with brown coal intercalations. Due to such morphologic and geologic setting the study area isprone to slope instability. Failure apt soil massifs were assigned to 4 groups. Out of 32 identified landslides, 9 were selected for detailed examination. To register a nature and rate of failures a complex monitoring system was installed on slopes where the selected landslides resulted in severe damages to municipal infrastructure. The system was facilitated with inclinometers andpiezometers, supported by a network of GPS-RTK geodetic benchmarks as well as with a recording weather station. The performed examination revealed that the most unfavourable arrangement of the layers is, when under a non-cohesive soil (e.g. sand, gravel) lies a cohesive impermeable layer (e.g. clay, loam). The landslides are rather shallow ones (except 2 incidents) with slow rate of displacement of an order offew mm/year. The landslide triggeringfactor is water originatingfrom precipitation and snow melting. Influence of water was especially significant in early Spring 2011, due to the combined effect ofsnow melting and infiltration of thawing water originating from the former, exceptionally high rainfalls. The influence of hydrologic conditions on slope deformations is complex. There is a significant timelag between a movement initiation and unfavourable hydrometeorological conditions. That is exemplified with the landslide that was initiated in February-March 2011 in consequence of atmospheric conditions of November-December 2010. The obtained results formed the background for inventing engineering treatment measures aiming at current remedial stabilization of slopes and mitigation ofpossible landsliding in the future.
5
Content available remote Modelowanie dynamiki warstwy gruntu na stole sejsmicznym
PL
Wyniki badań warstwy gruntu niespoistego na stole sejsmicznym. Analiza osiadań warstwy gruntu suchego poddanego poziomym drganiom o zadanej częstości i amplitudzie przyspieszenia, głównie harmonicznego oraz dynamiki warstwy nawodnionego gruntu, przy ustalonej amplitudzie poziomego przyspieszenia oraz różnych częstościach. Algorytm analizy teoretycznej problemu upłynnienia warstwy i podstawowe parametry badanego gruntu.
EN
The results of shaking table tests carried out on non-cohesive soil layer. The analysis of the settlement of dry soil layer subjected to horizontal vibrations for given frequencies and acceleration amplitudes, mainly harmonic and the dynamics of saturated soil layer for given amplitude of the horizontal acceleration and at various frequencies. The algorithm of theoretical analysis of the problem together with parameters of the soil.
PL
Przedstawiono wyniki badań doświadczalnych ściany oporowej z gruntu zbrojonego sztywnym i odkształcalnym zbrojeniem przy obciążeniu stemplem. Badania wykonano w celu porównania wpływu podatności zbrojenia na mechanizm zniszczenia, nośność graniczną i odkształcenia konstrukcji. Doświadczenia przeprowadzono z piaskiem jako ośrodkiem gruntowym oraz ze stosunkowo sztywną folią aluminiową i odkształcalną gazą jako zbrojeniem. Wykazano, że nośność graniczna konstrukcji z podatnym zbrojeniem była wyraźnie większa. Jednakże przy tym rodzaju zbrojenia, wystąpiły znacznie większe deformacje zarówno masywu, jak i lica modelu oraz wielokrotnie większe zagłębienie stempla, natomiast kształt strefy deformacji był w obu przypadkach podobny.
EN
The results of experiments performed on the small scale models of reinforces soil retaining wall loaded on its crest with the footing are presented. The influence of reinforcement’s stiffness on failure mechanism, ultimate value of external load and the deformation of construction are tested. The results confirm significant influence of reinforcement stiffness on the structure deformation. Both the footing displacement at the wall crest and the deformation of the model measured at failure in the tests with extensible reinforcement are much higher than those where the stiff reinforcement is applied. It is also shown that the critical load of the model wall with extensible reinforcement is higher than that with the stiffer strips.
PL
System monitorowania zboczy osuwiskowych na terenie Koronowa. Charakterystyka obszaru objętego badaniami i osuwisk. Zasady systemu monitorowania osuwisk i metody pomiarowe. Wybrane wyniki monitorowania, w tym warunki hydrologiczne, hydrogeologiczne oraz procesy deformacji zboczy osuwiskowych.
EN
The monitoring system of the landslide slopes in Koronowo region. Characteristics of the region and landslides. Principles of the monitoring system as well as measurement methods. Selected results concerning hydrological, hydrogeological conditions and deformation processes of the landslide slopes.
EN
Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.
PL
Mechanizmy zniszczenia konstrukcji z gruntu zbrojonego. Definicja słabego i mocnego zbrojenia. Metodyka badań modelowych: stanowisko badawcze, parametry gruntu i zbrojenia, zakres badań. Analiza wyników oraz wpływu podłoża na nośność ściany oporowej z gruntu zbrojonego.
EN
Failure mechanisms of reinforced soil constructions. Definitions of weak and strong reinforcement. Methodology of model tests: lab stand, soil and reinforcement parameters, scope of tests. Analysis of the results and the influence of a subsoil on the bearing capacity of reinforced soil retaining wall.
10
PL
Przy projektowaniu ścian oporowych z gruntu zbrojonego, często nie rozpatruje się wpływu podłoża na nośność graniczną takiej konstrukcji. Tymczasem, jak wynika z badań doświadczalnych i obliczeń numerycznych, w pewnych warunkach wpływ ten może być bardzo istotny. Zatem stosowanie podczas projektowania metod nie uwzględniających podłoża, może być przyczyną błędnego oszacowania nośności i w konsekwencji - prowadzić do awarii tak zaprojektowanych konstrukcji. W pracy przedstawiono badania eksperymentalne w małej skali oraz analizę numeryczną konstrukcji pełnowymiarowej w warunkach współpracy z podłożem. W obu przypadkach otrzymano wyniki wskazujące na możliwość spadku nośności granicznej ściany oporowej z gruntu zbrojonego, gdy strefa zniszczenia obejmie również podłoże.
EN
To date, in the design methods of reinforced soil (RS) retaining wall, an adjacent subsoil generally has been ignored in the analysis. However, the results of model tests and numerical analysis show that such approach can cause an incorrect prediction of ultimate external load and thus may lead to a failure of the structure. This paper presents the theoretical analysis, in which both RS construction and the subsoil are regarded. The tests of model with strongly reinforced RS wall are described, where failure loads and failure mechanisms are investigated. It is shown that the failure with the slip line passing entirely within the reinforced zone, is caused by larger ultimate external load than that associated with slip line also being beneath the wall toe i.e. in the subsoil.
PL
Opisano awarie geotechniczną spowodowaną obsunięciem się gruntu podczas wykonywania wykopu pod budowę domu jednorodzinnego. Przedstawiono historię awarii, omówiono przyczyny powstania osuwiska oraz zastosowane zabezpieczenie, uznane za najbardziej korzystne z punktu widzenia kosztów i oczekiwań inwestora.
EN
The landslide has been carried out by the execution of excavation under single family house. The reason of emerging slope failure and applied safegards favorable for investor are described.
PL
W pracy opisano badania modelowe pionowej ściany oporowej z gruntu zbrojonego, wykonane w celu rozpoznania wpływu ilości warstw zbrojenia na nośność i sposób zniszczenia konstrukcji obciążonej fundamentem pasmowym. Przeprowadzono 5 serii doświadczeń z modelami o jednakowej wysokości i ilości zbrojenia, natomiast ze zróżnicowanymi odstępami między warstwami zbrojenia. Nie stwierdzono istotnego wpływu ilości warstw gruntu i zbrojenia na nośność graniczną, mechanizm zniszczenia i wysokość bryły odłamu.
EN
The paper presents the model tests performed on the vertical reinforced soil (RS) retaining wall. The purpose of these experiments was to investigate the effects of the number of reinforcement spacing on the critical load and failure mechanism of RS structure loaded with strip footing. Five series of tests were performed. Each model wall had the same height and was reinforced with the same amount of reinforcement distributed with the different reinforcement spacing. It was shown, that the distance between the spacing had no significant effect on critical load, failure mechanism and the height of failure zone.
PL
Analiza mechanizmów współpracy i stateczności pionowych ścian oporowych z gruntu zbrojonego i podłoża gruntowego. Metodyka i zakres badań modelowych. Wyniki jakościowe i ilościowe badań modelowych i ich analiza.
EN
The analysis of interaction mechanisms and stability of vertical reinforced soil retaining walls and a subsoil. Methodology and the range of model tests. Qualitative and qualitative results and its analysis.
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