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Alluvial deposits as a subsoil and material for basic hydro-technical constructions

Wierzbicki J., Stefaniak K.

Journal of Ecological Engineering

2015

Vol. 16, nr 5

176--182

The article presents an analysis of geotechnical parameters of the alluvial deposit (the areas of the Vistula and Warta river valleys) with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. Strength and deformation parameters of the subsoil tested were identified by the CPTU (cone penetration test) and DMT (flat dilatometer test) methods, as well as by the vane test (VT). The article includes the analysis of overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 4 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne’s formula (1995) was used to determine the M0 modulus from the CPTU test. The usefulness of the alluvial deposit as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterized by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition. On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.

The evolution of a Weichselian proglacial lake in NW Poland as revealed by static penetration tests

Wierzbicki Jędrzej, Paluszkiewicz Renata, Paluszkiewicz Ryszard

Geologos

2011

Vol. 17, No. 2

111--119

The lithology, structure and geophysical characteristics of the glaciolacustrine clays deposited in the Wierzchowo proglacial lake were determined using static penetration tests (CPTU) in combination with standard lithological measurements. The deposits are divided into four lithological units (R1 to R4) on the basis of overconsolidation. Units R3 and R4 are separated by mass-flow deposits. The depositional conditions history of the lake result represent four phases: (1) an initial (low-energy) phase with the deposition of the rhythmically laminated sediments of units R1 and R2, which are divided by an erosional interval; (2) a phase of non-deposition with some desiccation structures and extended consolidation of sediments; (3) the main phase characterised by deposition of the rhythmically laminated sediments of unit R3; and finally, (4) the youngest phase, which represents alternations of deposition and erosion. The results show that sedimentation in the Wierzchowo proglacial lake was less continuous, and that the depositional processes were more complex than in the neighboring Złocieniec glacial lake.