CONSTITUTIVE MODELLING OF COARSE GRAINED SOILS FOR EARTH AND ROCKFILL DAMS The constitutive modelling of coarse grained soils is one paramount, but often neglected aspect for the prediction of the dam response. Such observation is even more relevant when considering the typical complexity of the dam loading conditions, mostly determined by water fluctuations and seismic excitations. The present work is aimed to provide, based on an experimental campaign and on a subsequent theoretical analysis, a contribution to define the main characters of the stress-strain response of coarse grained soils under complex testing conditions. In the experimental campaign several triaxial tests have been performed on artificially reconstituted samples, with the aim of detecting the effects of compaction, stress level, history and path on the stress-strain response of soil. Taking advantage of particularly high precise laboratory measurements the theoretical analysis could be carried out in the framework of elasto-plasticity, starting from very low strain levels. The elastic stress-strain response has been modelled by a cross-isotropic model defined into the literature. The plastic strains, for monotonic and cyclic loading, have been simulated by means of a critical state model where the shear strain development is expressed based on an upper bound surface. This latter and the flow rules are defined as a function of a soil state variable , combining the volumetric and the stress state of soil. A satisfactory agreement has been observed among the theoretical and experimental curves obtained for different stress levels, stress paths and soil density. Finally the stiffness decay and the damping increase with shear strains have been modelled for cyclic loading, finding a strong correlation between these functions and the soil state variable.

Modellazione costitutiva dei terreni a grana grossa impiegati per la realizzazione di dighe in materiali sciolti

MODONI, Giuseppe
2008

Abstract

CONSTITUTIVE MODELLING OF COARSE GRAINED SOILS FOR EARTH AND ROCKFILL DAMS The constitutive modelling of coarse grained soils is one paramount, but often neglected aspect for the prediction of the dam response. Such observation is even more relevant when considering the typical complexity of the dam loading conditions, mostly determined by water fluctuations and seismic excitations. The present work is aimed to provide, based on an experimental campaign and on a subsequent theoretical analysis, a contribution to define the main characters of the stress-strain response of coarse grained soils under complex testing conditions. In the experimental campaign several triaxial tests have been performed on artificially reconstituted samples, with the aim of detecting the effects of compaction, stress level, history and path on the stress-strain response of soil. Taking advantage of particularly high precise laboratory measurements the theoretical analysis could be carried out in the framework of elasto-plasticity, starting from very low strain levels. The elastic stress-strain response has been modelled by a cross-isotropic model defined into the literature. The plastic strains, for monotonic and cyclic loading, have been simulated by means of a critical state model where the shear strain development is expressed based on an upper bound surface. This latter and the flow rules are defined as a function of a soil state variable , combining the volumetric and the stress state of soil. A satisfactory agreement has been observed among the theoretical and experimental curves obtained for different stress levels, stress paths and soil density. Finally the stiffness decay and the damping increase with shear strains have been modelled for cyclic loading, finding a strong correlation between these functions and the soil state variable.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11580/8969
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