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Ocena efektów prekonsolidacyjnych na podstawie charakterystyki ściśliwości iłów zastoiskowych okolic Warszawy

100%

Zawrzykraj P.

Geologos

2007

tom Vol. 11

499--508

Niniejszy artykuł zawiera rezultaty badań terenowych i laboratoryjnych dotyczące prekonsolidacji plejstoceńskich iłów zastoiskowych z okolic Warszawy. Prezentowane wyniki dotyczą analizy ściśliwości wspomnianych gruntów pochodzących z okresu zlodowacenia Wisły. W oparciu o badania przeprowadzone w konsolidometrze Rowe’a oraz przy użyciu sondy statycznej CPT i dylatometru Marchettiego autor określił wielkość naprężenia prekonsolidacji oraz podjął próbę wyjaśnienia otrzymanych wyników.

In this paper the results of the study of overconsolidation ratio OCR of ice-dammed clays from the vicinity of Warsaw are presented. Results concern ice-dammed clays compression analysis formed during Vistula glaciation. Tests have been performed by using Rowe consolidometer, static sounding CPT and Marchetti’s dilatometer test. Author tries to explain obtained results of carried out studies.

Ettringite as a factor causing structural strengthening of fluvial sand from the Praski terrace (Warsaw, Poland)

51%

Zawrzykraj P. , Rydelek P. , Bąkowska A. , Cabalski K.

Acta Geologica Polonica

2022

tom Vol. 72, no. 4

519--528

Engineering activity may lead to uncontrolled changes in the geological environment. This paper presents an example of structural changes in fluvial sand of the Praski terrace (in Warsaw) caused by the activity of a temporary concrete batching plant. Our investigations made it possible to identify the material responsible for the structural anomalies observed in the bottom of the trench excavation. The compound responsible for the cementation phenomenon was identified as ettringite – hydrated calcium aluminosulphate: Ca6Al2[(OH)12(SO4)3]·26H2O. The source of ettringite were most probably significant volumes of contaminants coming from the temporary concrete batching plant (e.g., from the rinsing of concrete mixers and/or installations for concrete storage and transportation). While penetrating into the ground, ettringite caused extensive cementation of the soil mass, mainly in the saturation zone. As a result, the mineral (chemical) composition of the inter-grain space changed and the structure of the sand was strengthened. The estimated zone of volumetric changes in soil properties was about 6 thousand m3. However, analysis of the chemical composition of groundwater for its potential sulphate contamination, did not reveal any anomalous concentrations of sulphates.

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

32%

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

Acta Geologica Polonica

2022

tom Vol. 72, no. 4

529--555

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.