Wyniki wyszukiwania - Biblioteka Nauki

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Ocena zdolności do zmian deformacyjnych iłów mio-plioceńskich z poligonu badawczego STEGNY w Warszawie

100%

Barański M. , Wójcik E.

Geologos

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2007

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tom Vol. 11

413--420

PL

Zmiany deformacyjne zachodzą w gruntach spoistych w efekcie współdziałania fazy stałej gruntu z fazą ciekłą. W artykule przedstawiona jest kompleksowa, geologiczno-inżynierska ocena zdolności do zmian objętościowych prze- konsolidowanych iłów mio-plioceńskich z poligonu badawczego STEGNY w Warszawie. Do oceny wykorzystano: skład granulometryczny i mineralny, podstawowe właściwości fizyczne oraz parametry gruntowe, takie jak: powierzchnia właściwa, pojemność sorpcyjna, pęcznienie swobodne, ciśnienie pęcznienia, ciśnienie ssania oraz charakterystyki w postaci krzywych retencji iłów.

EN

Deformation changes occur in cohesive soils as a result of co-operation of their solid and liquid phases. The paper presents comprehensive, geological engineering evaluation of ability to volume changes overconsolidated mio-pliocene clay from site experimentation site STEGNY in Warsaw. For the evaluation of these changes grading and mineral composition, basic physical properties and soil parameters such as: specific surface, MBC, free swelling, swell pressure, suction pressure and soil-water characteristic curves were used.

2

Microstructural changes of expansive clays during dehydration caused by suction pressure - a case study of Miocene to Pliocene clays from Warsaw (Poland)

80%

Wójcik E. , Trzciński J. , Łądkiewicz-Krochmal K.

Acta Geologica Polonica

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2019

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tom Vol. 69, no. 3

465--488

EN

This paper presents the qualitative and quantitative characteristics of microstructures of Neogene clays from Warsaw, Poland. Scanning Electron Microscope (SEM) studies were used for the microstructural analysis of natural clays and clay pastes. Qualitative microstructural changes were observed: from a honeycomb microstructure for the initial clay paste to a turbulent microstructure for the dried paste. It was also noticed that water loss caused by the increase of the suction pressure had a significant impact on the microstructural transformations. Significant changes in the quantitative values of the pore space parameters were also observed. Increase of suction pressure and water loss caused a decrease in porosity and changes in the values of morphometric parameters, such as pore distribution; for example, a significant increase of the number of pores of 0−10 μm size and changes in the geometric parameters of the pore space were noticed with the increase of suction pressure. The pore space with larger isometric pores was modified into a pore space with the dominance of small anisometric and fissure-like pores. The increased degree of anisotropy from a poorly-oriented to a highly-oriented microstructure was also observed. After rapid shrinkage the reduction in the number of pores, maximum pore diameter, and total pore perimeter was recorded. The process of rapid water loss induced the closure of very small pores. A similar effect was observed during the increase of the suction pressure, where the closure of pore space of the clay pastes was observed very clearly.

3

Effects of hydrocarbon contamination on the engineering geological properties of Neogene clays and Pleistocene glacial tills from Central Poland

51%

Dobak P. , Izdebska-Mucha D. , Stajszczak P. , Wójcik E. , Kiełbasiński K. , Gawriuczenkow I. , Szczepański T. , Zawrzykraj P. , Bąkowska A.

Acta Geologica Polonica

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2022

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tom Vol. 72, no. 4

529--555

EN

Petroleum products influence the engineering behaviour of the soil. Neogene clays and glacial tills from Central Poland were tested under laboratory conditions to evaluate the changes of selected physical and mechanical parameters: particle size distribution, particle density, swelling, shear strength and permeability. Four petroleum products were used in the experiments: diesel fuel, kerosene, jet fuel and mineral engine oil. The study revealed that even for the lowest degree of contamination the values of physical and mechanical properties of the soils changed significantly. Greater variation can be expected in soils contaminated with high-viscosity compounds. Also, higher relative changes were found for glacial tills than for Neogene clays. Consolidation tests revealed changes in soil permeability depending on the soil composition and the physical properties of the contaminant – considerable reduction of permeability was observed for glacial tills contaminated with light Jet fuel, while the reduction was lower for Neogene clays. The obtained results indicate the role of mesopores and the dimensionless pore pressure coefficient in changes of soil permeability. The methodological issues regarding testing and analysing the hydrocarbon-contaminated soils were also presented and discussed, which might be useful for researchers studying contaminated soils.