Variability of overconsolidated soils from Poland in geotechnical practice

Abstract

The advantages of establishing databases of soil parameters are recognized within the geotechnical community. Especially, statistical description of soils is necessary tool for establishing probability distribution functions used in reliability based design framework and in standard deterministic approach of limit state design; previous knowledge, comparable experience, and engineering judgement, all play a major role in the selection process of characteristic values of most essential parameters. This is often done in face of limited amount of data from site investigation. The paper presents preliminary database compilation attempt for some parameters of overconsolidated glacial tills and clays from Poland. Due to a rapid growth of infrastructure and cities, analysis of already gathered data is essential for providing engineers with guidance on the variability of soil conditions, which is most noticeable in the case of fine‐grained overconsolidated strata. Focus is given to parameters obtained from triaxial laboratory tests, including small‐strain shear stiffness obtained from Bender Element Test.

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

“…3). In general, the shear wave values for loess correspond to the results obtained for silts and glacial clay, and fall between the values obtained for these soils [61]. This is also due to their specificity, which is manifested at the level of microstructure.…”

“…The geographical and geomorphological distribution of sampling locations is related to geological history of the investigated strata and the three major glaciation periods that resulted in their significant preconsolidation (clays and tills), loess are normal consolidated. To assess the properties of small-strain stiffness, a database for clays and tills described in detail in the work [61] was used. Against this background, the characteristics of loess as a problem soil due to the phenomenon of collapsed subsidence are presented.…”

“…Therefore, the use of a database, as a complementary source of information, may be an interesting alternative for implementation in engineering practice. Although it cannot be treated as a substitute for the site-specific tests, it can significantly increase the reliability of parameter estimation and offer an additional guidance in selection of their characteristic values [8].…”

Evaluation of Stiffness Degradation Curves from in Situ Tests in Various Soil Types

“…Generated and received S-and P-waves allow for estimating the Poisson's coefficient and the initial deformation modulus E0 of the tested soil. More details about this equipment and technical information were presented in [7], [12], [62].…”

“…1. More detailed characteristic and statistical distributions for analyzed soils were presented by Bogusz and Witowski [7]. The tests were conducted at the confining pressures between 15 kPa to 2000 kPa, with most data is range from 100 up to 500 kPa.…”