Abstract

Displacement piles belong to a group of technologies whose main idea is to install or make a pile without extracting ground material. According to definition, contained in PN-EN:1997-1:2008, displacement piles should be considered as driven, pressed in using vibrators and made with the use of spread augers. The classification of piles used so far with regard to the technology of execution is modified. An additional element is the emergence of new materials and plastics used in the construction of piles. The paper presents technological changes concerning not only the method of construction, but also the materials used. Another aspect is the methods of calculating the load-bearing capacity and settlement of piles. With acceptance for use the PN-EN:1997-1:2008 standard in 2010, it was necessary to change the approaches applied that based on many years of experience and tradition. The treatment of old methods was undertaken by defining coefficients allowing extrapolation of the load capacity from the range of critical values to the limit values. To a large extent these are empirical procedures. The main determinant in the process of designing and then verifying the load-bearing capacity of piles has been the determination of the force that causes settlement equal to 10% of the pile diameter. The best method in this case is to forecast the full load-settlement characteristics. The paper presents methods based on a hyperbolic model of the settlement curve, adopted mainly in tranformational functions, and a complex linear- exponential model, which reflects with high accuracy the cooperation of the substrate with displacement piles with a Increased base. On the basis of the collected data, a comparative analysis of particular displacement piles technologies was made. The characteristic elements of cooperation between the subsoil and piles were defined depending on the method of their execution. The usefulness of individual methods of load-bearing capacity calculation depending on the pile technology was determined.

Citations

Authors (2)