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EN
The article presents the results of CRL (Constant Rate of Loading) tests on Mio-Pliocene clays contaminated with Jet A1 aviation fuel and mineral oil 15W40. The study has shown that the compressibility of fine-grained soils contaminated with hydrocarbons during a constant rate of loading tests depends on the adopted loading velocity, as well as on properties of oil contaminants and their content in the soil pores. The implemented laboratory testprogram shows that the contamination of fine-grained soils with hydrocarbons increases their compressibility. Moreover, it has been stated that the CRL test method may be recommended in the compressibility research of fine-grained soils contaminated with hydrocarbons.
EN
The article presents the results of CRL research on glacial till contaminated with JET A1 aviation fuel and mineral oil 15W40. The conducted research has shown that the compressibility of fine grained soils contaminated with hydrocarbons during a constant rate of loading tests depends on the physical properties of the soil, properties of oil contaminants, their content in the soil pores as well as the adopted loading velocity. The implemented laboratory test program shows that the contamination of glacial till with hydrocarbons increases their compressibility. Moreover, this research shows that the CRL test method may be recommended in the compressibility research of fine grained soils contaminated with hydrocarbons.
EN
The substrate, whose compressibility has been analysed, served as subsoil for indirect foundations of bridges. A significant settlement of foundations was recorded while performing load tests. The results of the analysis indicate the specific structure of the Krakowiec Clays, as the cause of insufficient bearing capacity of piles. Small thickness of clay and silt layers prevents their separation, and certainly does not allow treating them as two soil types with different properties. The tested soil should be considered as a kind of natural composite, whose characteristics are unlikely to be "the resultant" of properties of constituent soils. Despite the high soil strength (very high values of strength parameters), the measured oedometer compression modules were significantly different from the standard attributed to this type of soils. The values of oedometer compression modules correspond with those prescribed by back analysis of settlement measured during the load test of piles. They were tested on natural undisturbed samples and on prepared samples of different humidities (from soil paste). The results were compared with those obtained by other researchers for soils of similar origin and alike physical properties.
PL
W związku ze spotykanymi niekiedy opiniami, co do potrzeby oceny ciśnienia prekonsolidowania [wzór] przy wyznaczaniu osiadań podłoża gruntowego, zostało pokazane, że nie jest to tak oczywiste. Zagadnienie to omówiono na przykładzie kilku charakterystycznych - ze względu na typ prekonsolidowania - zachowań się gruntów (wykresy krzywych ściśliwości). Zwrócono uwagę na "naturalne" zmniejszanie się ściśliwości gruntów normalnie skonsolidowanych, przy wzroście ciśnienia przez nie przenoszonego. W wyniku tego przedział naprężeń w którym relacje (wzór) mogą być uznane za wprost proporcjonalne - poszerza się, a styczne moduły ściśliwości przyjmują zbliżone wartości. Jedynie w gruntach bardzo luźnych, z makrostrukturą, lub poddanych obciążeniu mniejszemu od wywołanego nadkładem, wielkość ciśnienia prekonsolidowania może mieć istotne znaczenie przy wyznaczaniu osiadania podłoża.
EN
In the opinion of some scientists and engineers the knowledge of the preconsolidation pressure [formula] is a requisite for the evaluation of subsoil subsidence. The aim of the present paper is to demonstrate that such knowledge is not required in every instance. The problem is discussed taking as examples several compressibility curves for soils exhibiting different types of overconsolidation (due to unloading or aging, or of a structural nature) which is related to the stress value. It seems worth remembering that the compressibility of normally consolidated soils decreases when stresses increase. This means that the stress interval where the relations ([formula]) are linear becomes wider.
PL
W pracy przedstawiono wyniki laboratoryjnych badań ściśliwości gruntów pylastych. Do badań wytypowano próbę gruntu pylastego z rejonu Wrocławia. Grunty pylaste stwarzają szereg problemów w geoinżynierii. Struktura tych gruntów charakteryzuje się dużą wrażliwością na zmiany wilgotności, co powoduje szybkie zmiany właściwości inżynierskich wraz z przejściem ze stanu nienasyconego do nasyconego wodą. W artykule oceniono wrażliwość struktury gruntów pylastych na zmiany wilgotności poprzez porównanie charakterystyk ściśliwości prób gruntów pylastych o naturalnej strukturze, początkowo nasyconych jak i nienasyconych wodą z charakterystykami otrzymanymi z prób gruntów preparowanych w laboratorium.
EN
The results of laboratory examinations, of silty soil compressibility were presented. The soil sample have been taken from Wrocław area. Silty soil are creating a number of problems in geoengineering. The soil structure is characterized by a great sensitivity to changes water content what causes fast changes of engineering properties caused among others with change of the state from the unsaturated to saturated. In the paper a silty soil structure sensitivity was examined for the water content changes. The assessment were done by comparing of the oedometer curve get from test of soil about the natural structure, at first saturated as well as unsaturated with water, with oedometer curve gets from soil sample about the structure prepared in laboratory.
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