273 research outputs found
Numerical modeling of pile penetration in silica sands considering the effect of grain breakage
International audienceCurrent numerical platforms rarely consider the effect of grain breakage in the design of sandy soil foundations. This paper presents an enhanced platform for large deformation analyses which considers the effect of grain breakage during pile penetration in silica sand. For this purpose, a model based on critical state theory has been developed within the framework of multisurface plasticity to account in the same constitutive platform the effect of stress dilatancy and particle fragmentation. Furthermore, to implement the underlying constitutive equations into a finite element code, a stress integration scheme has been adopted by extending a cutting plane algorithm to the model with multiple yielding mechanisms. A laboratory model test and a series of centrifuge tests of pile penetration are simulated to verify the performance of the selected constitutive approach in terms of pile resistance and grain breakage distribution, with the parameters of sand calibrated through a set of drained triaxial compression tests from low to very high confining pressure. Some extra features of the enhanced platform are also discussed, such as: i) the effect of sand crushability on pile resistance and ii) the nonlinear relation of pile resistance to sand density. The proposed findings demonstrate the capability of this numerical platform to proper design of pile foundation in sandy soils and highlight the interplay between stress dilatancy and grain breakage mechanisms during pile penetration processes
Hyperon polarization and its correlation with directed flow in high-energy nuclear collisions
We investigate the hyperon polarization and its correlation with the directed
flow of the quark-gluon plasma (QGP) in non-central Au+Au collisions at
GeV. A modified 3-dimensional (3D) Glauber model
is developed and coupled to a (3+1)-D viscous hydrodynamic evolution of the
QGP. Within this framework, we obtain a satisfactory simultaneous description
of the directed flow of identified particles and polarization, and
show sensitivity of polarization to both the tilted geometry and the
longitudinal flow profile of the QGP. A non-monotonic transverse momentum
dependence of the polarization is found in our calculation, which is
absent from hydrodynamic simulation using other initialization methods and can
be tested by future experimental data with higher precision. A strong
correlation (or anti-correlation) is found between the global polarization and
directed flow of when the longitudinal flow field (or medium
deformation) varies, indicating the common origin of these two quantities.
Therefore, a combination of these observables may provide a more stringent
constraint on the initial condition of the QGP.Comment: 15 pages, 12 figures, any comments are welcom
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