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Results of the “DPDT-Auger” research project on screw displacement piles

Krasiński Adam, Słabek Andrzej, Więcławski Paweł, Wiszniewski Mateusz, Kusio Tomasz, Tisler Witold

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 3

89--99

EN

The main objective of the “DPDT-Auger” research project was to test the prototype DPDT auger for forming screw displacement piles in the ground (patented in Poland in 2020). An additional aim was to develop design methods and rules for the making of such piles. The augers and piles were first tested on a model scale, and then more extensively in the real scale on experimental field plots. The results found the overall functionality of the DPDT auger to be good, and in several aspects better than that of the SDP auger. The load-bearing capacities and Q-s characteristics of piles made with both augers were considered comparable. All the conducted tests and their derived dependencies together with the results of in situ subsoil tests allowed for the development of empirical calculation methods and prognostic procedures, useful for designing and producing piles with DPDT and SDP augers. FEM numerical simulation rules for the considered piles were also developed, verified and calibrated by the results of real pile tests. This article describes only the most important final results of the research project but not the detailed results of the numerous tests and analyses that were carried out. Also omitted are the results of model tests and numerical simulations, as well as the implementation and acceptance recommendations, as they have already been or will be the subject of separate publications.

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Identification of residual force in static load tests on instrumented screw displacement piles

Krasiński Adam, Wiszniewski Mateusz

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr 4

438--451

EN

Occurrence of the so-called residual force of an unknown value significantly disturbs interpretation of static load tests performed on piles equipped with additional measuring instruments. Screw displacement piles are the piling technology in which the residual force phenomenon is very common. Its formation mechanism is closely related to the installation method of this type of piles, which initiates generation of negative pile skin friction without any additional external factors. Knowledge of the value and distribution of a residual force (trapped in a pile shaft before starting the load test) is a necessary condition for the proper interpretation of instrumented pile test results. In this article, a clear and easy-to-use method of residual force identification, based on the analysis of shaft deformations recorded during pile unloading is presented. The method was successfully verified on two pile examples and proved to be effective and practical.

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Mechanizm współpracy z gruntem pali prefabrykowanych wbijanych w świetle próbnych obciążeń pali oprzyrządowanych

Krasiński Adam, Gwizdała Kazimierz, Kusio Tomasz, Więcławski Paweł, Wiszniewski Mateusz

Inżynieria Morska i Geotechnika

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2020

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nr 2

72--82

PL

Opis i wyniki próbnych obciążeń statycznych dwóch pali prefabrykowanych wbijanych oprzyrządowanych pomiarowo. Analiza wpływu czasu i procesu wbijania na charakterystykę osiadania pali prefabrykowanych wbijanych. Identyfikacja siły rezydualnej w palu prefabrykowanym wbijanym i jej wpływ na interpretację pomiarów ekstensometrycznych w próbnym obciążeniu pala. Wnioski na temat problemów w interpretacji wyników badań pali prefabrykowanych wbijanych oprzyrządowanych pomiarowo.

EN

Description and results of two static load tests on instrumented precast driven piles. Analysis of time and pile driving process impact on the settlement characteristics of precast piles. Identification of the residual force in a driven pile and its impact on the interpretation of strain measurements in the pile load test. Conclusions on the results interpretation problems of load test on instrumented precast driven piles.