Abstract

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.

Citations

Author (1)