Reliability-based assessment of drilled displacement (DDS) piles bearing capacity using field tests and FEM

Abstract

The article deals with geotechnical design of pile foundations, especially by static load tests and by calculation using numerical models. The results of comparison analysis of bearing capacities drilling displacement system (DDS) boring piles obtained by static load tests and by standard are presented in article, as well as results of compression test of surrounding soil after DDS pile installation. Drilled Displacement System (DDS) piles are an innovative technology for pile foundations. These DDS piles are created by rotary drilling with a simultaneous full displacement of the soil in a horizontal direction. The optimal design of DDS piles can be obtained in soils that allow for a horizontal displacement, which causes an increase in the shaft’s resistance. Significant differences between experimental (Static Load Test by GOST) and design (by Kazakhstan Standards) values of bearing capacity of DDS pile show us incomplete usage of DDS technology resourced. The results of numerical analysis of DDS and traditional boring pile modeling by FEM (Plaxis 2D) are also presented in the paper. The numerical results have been presented with equivalent static load-settlement curve. By results of numerical analysis coefficient of surrounding work is defined. These investigations are important for un-derstanding of soil-pile interaction on problematical soft soils ground of Astana, Kazakhstan.