Podstawą w projektowaniu konstrukcji inżynierskiej lub jej elementów jest znajomość podłoża gruntowego, w szczególności jego parametrów geotechnicznych. Przedstawione opracowanie ma charakter analizy zmienności regionalnej parametrów geotechnicznych gruntów ilastych południowo-zachodniej Polski, pod względem stratygraficznym zaliczonych do utworów neogeńskich. W publikacji wykorzystano bieżące badania własne uzupełnione o archiwalne badania próbek gruntów ilastych pochodzących z Legnicy i Głogowa. Wyniki badań opracowano statystycznie oraz przedstawiono w formie tabelarycznej.
EN
The basis for the design of engineering structure or its elements is knowledge of the subsoil, in particular its geotechnical parameters. The study is a regional analysis of the variability of geotechnical parameters of clay soil of south-western Poland, stratigraphically classified as Neogene formation. The publication uses the author’s own study complemented by archival research of clay soil samples from Legnica and Głogów. The test results were statistically analyzed and presented in tabular form.
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 paper considers the use of high-resolution X-ray computed microtomography (μCT) as a possible method in engineering-geological laboratory research for indicating areas of weakness, location of fissures and determining homogeneity of clay samples. Furthermore, the studies were used to provide methodological guidance. Mio-Pliocene (Neogene) clay samples were taken from an excavation site of the Kopernik underground station in Warsaw. First, natural humidity, bulk density and fraction analyses of samples were made. Secondly, μCT scans were conducted, with the use of copper filters. In the final stage of the study, internal structure images for samples were processed and analysed. Furthermore, a numerical model of dry sample was developed. During the study it was observed that the increase of temperature caused by X-ray radiation has a destructive effect on the sample. This effect was eliminated by applying a protective layer on the sample, using engine oil. The article quantifies the ratio of radiation-heated fissure volume to dry sample volume and the natural fissure volume to sample volume. Moreover, sample areas with different densities or chemical composition were studied. The results lead to the conclusion that the μCT technique is applicable to characterise of Mio-Pliocene clay, supplying internal structure assessment and fissure quantification that allow for samples verification to further engineering geology in-depth analysis.
4
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
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.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.