Reinforcement of soil with stiff columnar inclusions is by far the most traditional and frequently adopted solution to face bearing failure and intolerable settlements of foundations. The equipments and construction procedures adopted to conjugate effective load transfer to the surrounding soil with faster and economical execution are among the most remarkable examples of inventiveness in geotechnical engineering. Nowadays a variety of technological developments is available to build new structures on difficult subsoil conditions, including innovative methods for the installation of piles and ground improvement techniques based on mixing of natural soil with cementing agents. However a rational approach for the choice of the most suitable foundation system should require careful analyses to be performed on the load settlement response of the single columnar elements. While these analyses are available in the literature for traditional pile types as a basis for empirical or sound theoretical design rules, only limited spotlike results can be found for new pile types and moreover for cemented soil columns. The present paper aims to fill this gap by performing a comparative analysis of the load settlement responses of different columnar inclusions. To this aim a large number of case studies has been collected, partly from the literature partly from original files of the authors, and classified based on the execution technology. Selected examples are analysed in the paper where axial loading tests conducted up to relatively large settlements are combined with geotechnical investigation of the subsoil. Hyperbolic interpolation of each load settlement curve is performed and a unifying scaling criterion is applied to the fitting parameters to account for the different dimensions of columns. Scaled parameters obtained from different tests are finally related to the subsoil properties in order to perform a comparative analysis of the trends derived for the different reinforcements. Interpretation of the differences observed on the bearing capacity and on the initial stiffness of the various columnar inclusions is given in the light of the different disturbance produced on the surrounding soil by the installation systems.
Load-settlement responses of columnar foundation reinforcements
MODONI, Giuseppe;
2012-01-01
Abstract
Reinforcement of soil with stiff columnar inclusions is by far the most traditional and frequently adopted solution to face bearing failure and intolerable settlements of foundations. The equipments and construction procedures adopted to conjugate effective load transfer to the surrounding soil with faster and economical execution are among the most remarkable examples of inventiveness in geotechnical engineering. Nowadays a variety of technological developments is available to build new structures on difficult subsoil conditions, including innovative methods for the installation of piles and ground improvement techniques based on mixing of natural soil with cementing agents. However a rational approach for the choice of the most suitable foundation system should require careful analyses to be performed on the load settlement response of the single columnar elements. While these analyses are available in the literature for traditional pile types as a basis for empirical or sound theoretical design rules, only limited spotlike results can be found for new pile types and moreover for cemented soil columns. The present paper aims to fill this gap by performing a comparative analysis of the load settlement responses of different columnar inclusions. To this aim a large number of case studies has been collected, partly from the literature partly from original files of the authors, and classified based on the execution technology. Selected examples are analysed in the paper where axial loading tests conducted up to relatively large settlements are combined with geotechnical investigation of the subsoil. Hyperbolic interpolation of each load settlement curve is performed and a unifying scaling criterion is applied to the fitting parameters to account for the different dimensions of columns. Scaled parameters obtained from different tests are finally related to the subsoil properties in order to perform a comparative analysis of the trends derived for the different reinforcements. Interpretation of the differences observed on the bearing capacity and on the initial stiffness of the various columnar inclusions is given in the light of the different disturbance produced on the surrounding soil by the installation systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
