Time dependent factors in pile quality and capacity control

This work presents the results of field testing and further analysis of length estimation and capacity of piles. Concerning the CFA pile quality control, the measured elastic wave velocities examined between the 5th and 15th day after the C20/25 concrete embedding ranged from 3,000-4,000 m/s. However, the standard deviation is relatively high, the time seems to be the crucial factor. Load tests (capacity tests) as well as the tests of the length and integrity of the foundation piles belong to the set of indispensable control procedures, which verify the design and the execution of pile foundations. Bearing in mind the applied piling technology and the soil conditions, it is necessary to define the minimal time span between the piling and the beginning of the tests. At the same time, the pressure from the contractors often causes the control procedures to begin and finish before that time. The research conducted at Wroclaw University of Technology shows that in the case of driven piles, the increase of capacity can be observed mainly in cohesive soils, where the reconsolidation of soil around the pile affects strongly the pile-soil shaft adhesion.