The paper presents the results of swell measurements of Neogene clays (Posnanian clay) from the Mazovia region with different grain size distribution and mineral composition. The study was conducted with model soil with initial moisture contents of 15%, 20%, 25% and 30%. The basic physical properties of clays, their mineral composition and swelling parameters such as free swelling index and swelling pressure were determined. Free swell index was correlated to liquid limit, plasticity index, clay content and water content. A very high fit was found for a proposed relationship between the free swell index and swell pressure which offers an inexpensive method of predicting swell pressure in the preliminary stages of site investigation.
W artykule przedstawiono studium przypadku oceny stateczności zbocza zlokalizowanego w południowej Polsce, w obszarze o skomplikowanej budowie geologicznej. Zaproponowano wieloetapową metodologię oceny stateczności zbocza. Zastosowane komplementarne techniki badawcze pozwoliły uzyskać dokładną i rzetelną ocenę stateczności analizowanego zbocza, a przedstawiona wieloetapowa procedura analizy uwarunkowań stateczności umożliwiła uwzględnienie różnych cech i mechanizmów destabilizujących stan równowagi, co pozwala na prognozowanie kierunków zagospodarowania przestrzennego.
EN
The multistage methodology of the slope stability analysis, based on a case study, is presented in the paper. The study area is located in southern Poland, where geological conditions are complex. A numerous complementary research techniques that were applied provided reliable and exact assessment of equilibrium state of the slope. The results have shown that presented multistep procedure takes into account various destabilizing factors and therefore enables the prediction of the future spatial planning.
The paper presents the results of swell index, swelling pressure and soil suction tests carried out on Neogene clays from Warsaw, depending on the water content, clay fraction, liquid limit, plasticity index, cation exchange capacity, and content of clay minerals and beidellite. These clays are considered expansive soils in Poland, as they are vulnerable to water content variations in the active zone, which result in their volume change and, in consequence, cause damage of foundations and other construction elements. A number of physical, chemical and mineral properties were determined for these clays. The swelling tests were carried out on samples precompacted in Proctor apparatus, at various initial values of water content. The analyses have shown exponential relation of swell index, swelling pressure and suction versus water content. In addition, the investigated relationship between the suction and swell characteristics of tested clays shows good correlation as a power function between these parameters. In addition, validity of correlations between fitting parameters of obtained relationships and soil index properties, such as clay fraction, liquid limit, plasticity index, cation exchange capacity, and content of clay minerals and beidellite, have been demonstrated. The empirical relations are characterized by high values of the correlation coefficient. A very high fit has also been found for a proposed relationship between the swell index and swelling pressure for tested clays.
This study concerns the modeling potential of slopes development with use of numerical stability calculations. Boundary conditions of performed numerical simulations are according to morphological and geological engineering conditions of the flysch slope shaped by weathering and surface mass movements. The multilaminate material model was used in order to imitate shale spatial variation in weathering zones. Furthermore, X-ray computed microtomography technique enabled for visualization of varied condition of shear surface extortion, which cause physical and strength parameters diversity. Calculation outputs show that geometry and location of deformation zones are affected by a model input strength parameter. The presented results confirm utility of numerical modeling as important aspect in the investigation and verification of spatiotemporal slope development cycle.
The paper attempts to answer the question which method provides an accurate assessment of organic matter content in the study of Mio-Pliocene clay. Samples were taken from the excavation of Copernicus Science Centre metro station. The soil was tested by three most common techniques: ignition loss method, reaction with hydrogen peroxide, and Tiurin method. Furthermore, thermal method (DTA) was used as a complex method for mineral composition (including organic matter) verification. Results of Tiurin and DTA methods provided information about the residual presence of organic matter in the Mio-Pliocene clay. Nonetheless, because of their simplicity, the commonly used methods are ignition loss and reaction with hydrogen peroxide. The results of ignition loss method were ~7 times higher than those of the other methods. The reaction with hydrogen peroxide method, revealed a negative result ~ –0.89%, due to oxidation of iron and hydration of its compounds. Based on these observations, it can be concluded that the Tiurin method is the recommended technique for the assessment of organic matter content in cohesive soils. However, for studies requiring high accuracy and reliability, the thermal method is recommended. It is important to pay special attention in organic matter evaluation particularly for commercial projects, because organic matter evaluation can result in a large increase in the cost of investment.
The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.
The article presents an assessment of the impact of the salt used in road construction on the swelling of Mio-Pliocene clays. The tests were performed on the clay samples taken from the Warsaw area. Different concentrations of sodium chloride and calcium chloride were used. A relatively high swelling values were determined, higher for clays diffused with calcium chloride than samples with sodium chloride and samples with deionized water. The swelling increases with the increase of salt concentration up to 5%. The swelling decreases with the salt concentrations higher than 5%.
Development of building projects in the Mazovia region causes the risk of their location on the soils of specific expansive properties. These properties, expressed as swelling or shrinkage, are a serious engineering problem. Many methods are used for the evaluation ofexpansiveness; both direct and indirect test methods are used. Tests were performed on clays from the areas of Warsaw, Dobre near Mińsk Mazowiecki and Mszczonów. Comparative analysis of expansive properties of Neogene clays is based on the results of laboratory tests of mineral composition, grain size distribution, moisture content, free swelling and swelling pressure. The tests have shown that the expansive properties ofclays from the Mazowsze region can have extremely high values, which causes the needfor individual determination of potential expan-siveness for different types of clays, depending on moisture content, swelling pressure and chemistry of the environment.
Artykuł poświęcony jest problematyce wyznaczania w laboratorium współczynnika filtracji, jednego z istotnych kryteriów doboru gruntu jako materiału izolacyjnego. Program badań obejmował 3 serie pomiarów współczynnika filtracji na próbkach gliny lodowcowej kompleksu północnopolskiego, założono w nim różne warunki gradientu hydraulicznego i naprężenia. Wyniki świadczą o znacznej zmienności współczynnika filtracji w zależności od warunków badania, co sygnalizuje potrzebę doprecyzowania istniejących wytycznych badań przepuszczalności.
EN
The paper focuses on the problems of determining the permeability coefficient, one of the important criteria for selecting the ground as a sealing material. The research program included three series of measurements of the permeability coefficient on samples from North-Polish complex till, using different conditions of stress and hydraulic gradient. The results show a considerable variability of the coefficient depending on the studied conditions, which indicates the need for research to clarify the existing guidelines for permeability studies.
Przedstawiono ocenę ekspansywności iłów plioceńskich z rejonu Dobrego. Stwierdzono, że iły te, znajdujące się w stanie półzwartym, charakteryzują się wysoką zawartością frakcji iłowej, w której dominującym minerałem ilastym jest Ca-beidelit. Mimo że charakteryzują się wysoką i bardzo wysoką potencjalną ekspansywnością, w warunkach naturalnych nie powinny stanowić zagrożenia ze względu na wysoki stopień nasycenia i niskie wartości ciśnienia pęcznienia.
EN
In this paper the evaluation of expansiveness of Pliocene clays from Dobre area was presented. It has been stated that these clays are in semi-solid state and are characterized by a high content of clay fraction with Ca-beidellit as a dominant clay mineral. Although the tested clays are characterized by high and very high potential expansiveness PE, in natural conditions they shall not constitute a threaf because of the high degree of saturation and low values of swelling pressure.
Projects for the storage of municipal waste involve systems of successive safety barriers consisting at least of a geomembrane and a natural mineral layer. “Poznań Clay” are among materials which can be used as a mineral layer. In this paper mineral layers standards from different countries are described. Studies of the important properties of “Poznań Clay” such as hydraulic conductivity, mineral composition, and void ratio are presented. Samples with undisturbed and disturbed structure were examined. Differences between properties of these samples are negligible.
Miocene clays of the Poznań series from Warsaw were analysed by scanning electron microscope. The influence of swelly pressure causes soil porosity to decrease slightly together with a reorientation of pores. They become more anisometric, while their original matrix microstructure acquires properties of matrix-turbulent microstructure.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.