The current possibility of obtaining financial resources from the European Union funds results in the increase of road investments in Poland. At the same time, Poland (together with Ukraine) is preparing for the organisation of EURO 2012. The majority of new engineering objects (bridges and viaducts) are founded on foundation piles. The construction of piles underneath the erected objects is preceded by the obligatory testing determined by the code of practice, and thus leads to the prolonging of the works execution. As it is in the whole EU, static testing constitutes the basic bearing capacity testing in accordance with local regulations (Polish code of practice) and, as follows, contract specifications. High-strain dynamic testing (CASE, CAPWAP, DLT, PDA) and integrity testing (PIT, SIT) used to be carried out as the additional control procedures, which provided the quality, and not quantity, assessment. However, for the recent years, dynamic testing has become in Poland an accepted method of pile capacity assessment. Kinetic bearing capacity testing (STATNAMIC, DYNATEST) is not frequently used.

This paper presents a case study of piling project and testing of a huge Commercial Centre in the south-western region of Poland. The overall pile driving works involved more than 2500 RC piles of a total length over 33 000 m. Assumption that the bearing capacity of a pile driven into cohesive soil may increase significantly in time (set-up effect), was the reason for the contractor to take the risk to accelerate the testing procedure. Usually, when the load test result indicates insufficient bearing capacity, the testing procedure may be repeated after a period required by the codes of practice. The possible later increase of pile bearing capacity adds up to additional safety margin for the design. In the case of sandy soils, reported by Jardine et al (2006) values of capacity increase amounting to app. 20% do not affect much pile bearing capacity and the design procedure. It is important to state that some authors have observed an opposite effect called relaxation, which can appear in silty soil. The authors of the paper, however, have never noticed this effect. On the contrary, the numerous static and dynamic testing of foundation piles designed for Auchan Commercial Centre in Raciborz (Poland) have proved a significant time-dependent increase of bearing capacity of piles driven in silt (reaching app. 67%).

The article presents the criteria of choosing dynamic formulas for analyzing the bearing capacities of driven piles based on rich static analysis. One of most reliable dynamic formula is the so-called Danish Formula (Sorensen & Hansen formula), widely used in Poland.

The article was published in Inżynieria Morska i Geotechnika, 3/2008

The article focuses on non-standard test loading of a two-pile group. The test aimed to compare the operation of a two-pile group and of a single pile.

The article was published in Inżynieria Morska i Geotechnika, 1/2008

The paper was published in conference materials: GEOTECHNICS 2006. Construction, Technologies, Materials and Monitoring. Slovakia. The High Tatras. 20-22.09.2006

The article was published in the periodical "Inżynieria Morska i Geotechnika", no. 4/2006

The article describes piling work within the project "Modernization of Domestic Road No. 3. Construction of Gorzów Wielkopolski Western By-Pass - Stage II ".

Kalejdoskop Budowlany - September 2005