Jakub Konkol

In this paper, the whole process of pile construction and performance during loading is modelled via large deformation finite element methods such as Coupled Eulerian Lagrangian (CEL) and Updated Lagrangian (UL). Numerical study consists of installation process, consolidation phase and following pile static load test (SLT). The Poznań site is chosen as the reference location for the numerical analysis, where series of pile SLTs have been performed in highly overconsolidated clay (OCR ≈ 12). The results of numerical analysis are compared with corresponding field tests and with so-called "wish-in-place" numerical model of pile, where no installation effects are taken into account. The advantages of using large deformation numerical analysis are presented and its application to the pile designing is shown.

In this paper the results of the cone penetration test (CPT) modeling with the arbitrary Lagrangian-Eulerian (ALE) formulation provided by Abaqus software package have been presented. The study compares the cone resistance and sleeve friction obtained in numerical analysis with values measured in soundings performed in the uniform layer of clayey soil in the Koszalin area. The clay layer was found to be slightly overconsolidated with OCR ranging from 3.5 to 4.5. The subsoil parameters used in the numerical model are based on laboratory tests data and the complementary CPT estimation. Evaluation of the most important factors influencing the numerical solution such as friction on the probe-soil interface and the undrained shear strength of the clay have been discussed. The possibilities of ALE method for soil parameters calibration are introduced and future challenges in large deformation problems modeling due to penetration issues are described.

In this paper, a numerical undrained analysis of pile jacking into the subsoil using Abaqus software suit has been presented. Two different approaches, including traditional Finite Element Method (FEM) and Arbitrary Lagrangian–Eulerian (ALE) formulation, were tested. In the first method, the soil was modelled as a two-phase medium and effective stress analysis was performed. In the second one (ALE), a single-phase medium was assumed and total stress analysis was carried out. The fitting between effective stress parameters and total stress parameters has been presented and both solutions have been compared. The results, discussion and verification of numerical analyzes have been introduced. Possible applications and limitations of large deformation modelling techniques have been explained.

Numerical simulations of a pile jacking were carried out. A Coupled Eulerian–Lagrangian (CEL) formulation was used to treat with large deformation problems. An Abaqus, a commercial Finite Element Method software suit, was used as a computing environment. The Mohr–Coulomb constitutive model was applied and the Coulomb model of friction was used to describe pile-soil interaction. Calculations were made for three different pile diameters. Toe and shaft unit resistances versus depth for each pile were investigated and plotted. CPT-based solutions were compared with the results of numerical simulations.

[PL] Rozwój modelowania zjawisk geotechnicznych w wirówce. Historia rozwoju urządzenia. Przyczyny wykorzystania wirówki geotechnicznej przez ośrodki naukowe i biura inżynieryjne. Obecny status urządzenia w edukacji i przemyśle. Podstawy teoretyczne badań modelowych w wirówce geotechnicznej. Lista wybranych zależności korelacyjnych. Przegląd i dyskusja wybranych współczynników skali.
[EN] A development in centrifuge technology. Its influence in geotechnical engineering. A review of the centrifuge history. The reasons of using geotechnical centrifuge in construction industry and in research studies. The main principles of centrifuge modelling. The origin of simulitude laws. The list of chosen scaling laws. A selected scale factors overview.

The problem of large deformations often occurs in geotechnical engineering. Numerical modeling of such issues is usually complex and tricky. The chosen solution has to implicate soil-soil and soil-structure interactions. In this paper, a review of the most popular numerical methods for large deformation problems is presented. The Coupled Eulerian-Lagrangian (CEL) method, the Arbitrary Lagrangian-Eulerian (ALE) method, the Smoothed Particle Hydrodynamics (SPH) method, the Particle Finite Element Method (PFEM) and the Material Point Method (MPM) are described. The basic concepts and features of these methods are shown. Also a comparison of these methods in terms of geotechnical engineering is made.

Geotechnical centrifuge modelling has been a world-wide used technology in
physical tests. In this papers a derivation of scaling laws by dimensional analysis for the
centrifugal modelling is presented. Basic principles of centrifuge modelling are described.
Scaling laws for slow events like consolidation and fast events like dynamic loads are
shown. The differences in scale factors for both processes are noticed. The aim of this paper
is to introduce geotechnical centrifuge technology to a wider Polish audience.

In this thesis the empirical equation for radial effective stress calculation after displacement pile installation and following consolidation phase has been proposed. The equation is based on the numerical studies performed with Updated Lagrangian, Arbitrary Lagrangian-Eulerian and Coupled Eulerian-Lagrangian formulations as well as the calibration procedure with database containing world-wide 30 pile static loading tests in cohesive soils. The empirical formula has been validated with 10 pile static load tests performed in Poznań clay and its reliability has been compared with 7 pile design methods. In this thesis, the description of research methodology and brief review of Finite Element Method with emphasis on large deformation formulations have been given. The key soil parameters which influence the radial stresses after pile installation and subsoil consolidation, both modelled numerically, have been identified. Next, the numerical methods have been validated with a high quality instrumented pile installation test in London clay and simulations of CPT and CPT-u soundings in Koszalin and Poznań clays, respectively. As a consequence of numerical tests interpretation, the general form of the empirical relation for radial effective stress has been provided. This relation has been calibrated with high quality, 30 pile static load tests. Next, the reliability of pile bearing capacity prediction with the proposed empirical formula has been checked using the database of all 75 piles and reference piles in Poznań site. Besides the validation of the author's equation for radial effective stress after installation and subsequent consolidation, the numerical calculation for the reference pile in Poznań site has been carried out. Numerical calculations include large deformation analysis where all pile construction steps have been taken into account and simplified finite element model where author's empirical formula have been adopted to predict the load-settlement response of the reference pile. Finally, the limitations of the proposed formula are provided and the further possible research directions due to pile installation effects are pointed out.