O precyzji sondowania statycznego na przykładzie badań gruntów przejściowych poletka badawczego AMU Morasko

Abstract

On the quality of CPTU results in terms of precision; a case of soft intermediate soils, AMU Morasko test site.A b s t r a c t. The Cone Penetration Test is one of the most versatile and widely used geotechnical tests over the world. Some differences in technical solutions between the equipment manufactured by different producers and the relatively quick wear of the penetrometer itself make the issue of quality and comparability of the CPTU results very actual. The tests were conducted in the testing ground of Adam Mickiewicz University in Poznań. The test site is located in the northern part of Poznañ, within a marginal zone of the Poznań Phase of the Weichselian (Vistulian) glaciation. The subsoil consists of glacial till of the Riss glaciation and glacial till of the Vistulian glaciation, separated by fluvioglacial sandy sediments and covered with fine and medium sands with single gravel grains. The quality of geotechnical parameters of the tested subsoil was assessed for the initial constrained modulus and undrained shear strength. To determine these parameters, static penetrometers produced by two different manufacturers were used. The tests and the results of analysis were performed in three stages. In the first stage, each penetrometer was used to investigate homogeneity and diversity of the subsoil structure in the test sites. The subsoil structure diversity was examined by grouping statistically similar Rf coefficient values along the profile. In the second stage, the level of accuracy and precision in the assessment of the corrected cone resistance – qt, frictionon the friction sleeve – fs, and pore pressure – u2 was determined for individual penetrometers. In the next stage, the differences between the constrained modulus and undrained shear strength were determined for both penetrometers. This analysis takes into account the level of precision of the corrected cone resistance.