Impact of ACIP Pile Drilling Technique on Subsurface Soil Density

Abstract

For the foundation of an industrial complex, auger-cast-in-place piles (ACIP-Piles) have been installed on behalf of the recommendation of a local geotechnical consultant. With respect to the poorly graded sand deposits and the high ground water table, the installation was critically reviewed with respect to the European Code DIN EN 1536. In the course of the installation process of a couple of working piles, extensive soil was drilled by the auger, which led to a loss of soil mass in the vicinity of the pile shafts. A detailed engineering analysis came to the conclusion, that the reasons of the damage can be attributed to a concurrence of the subsurface soil conditions, the chosen drilling technique, the choice of the contractor as well as the workmanship. However, a distinct soil loosening could also be measured by a plenty of cone penetration tests in the vicinity of those working piles, which have apparently been installed properly. Surprisingly, the compact sand layers were much more affected by the installation process than the loose deposits. These findings lead to the conclusion, that the installation process of ACIP piles has to be critically evaluated during the construction process and may become a decisive design influence in the case of a pile design by empirical pile capacity magnitudes.