Design of deep foundation for Osijek city water treatment plant

Abstract

Water Treatment Plant for the city of Osijek is situated on the riverbank of Drava River. The soil at the location consists of alluvial deposits with layers of soft soil to the depth of 16 m. One part of the construction area is covered with 4 m high fill material. For heavy loaded structures and large area basins and tanks, deep foundation was designed with full displacement concrete piles. The piles of d=40 cm are installed by using lost cone technique down to 2 m in the bearing stratum of dense sand. Bearing capacity of the piles is calculated according to geotechnical investigation works which consists of geotechnical borings, laboratory tests, in‐situ SPT and CPTU. The calculation methodology is given, regarding the selection of design values for pile skin and base resistance. The effect of addition filling on the construction area is evaluated by using finite element method in Plaxis 2D, to calculate the negative skin friction on the piles. After the pile construction, pile capacity was tested by dynamic load test. The comparison of predicted and tested results is given in the paper.