  The Sand Hypoplastic (SH) constitutive law by von Wolffersdorff (1996) is a
interesting hypoplastic model for soil mechanics. This model includes eight
parameters, usually calibrated using the oedometric (OE) and the drained
isotropically consolidated triaxial tests (CD). However, previous studies show
that the SH model calibration in the CD test has conflicting requirements in
predicting the evolution of stresses and strains.
  In this work, we study the SH model calibration over a wide range of testing
conditions using 12 OE and 25 CD tests by Wichtmann and Triantafyllidis (2016)
on the Karlsruhe sands. The parameter space is extensively explored via Genetic
Algorithm Optimization (GA) using the recently developed open-source software
GA-cal (available at \url{https://github.com/FraJoMen/GA-cal}). This
exploration allowed us to study the SH model's predictive limits and to
identify, using a multi-objective analysis, the main parameters governing the
compromise between the accurate prediction of stresses versus strain in the CD
tests.
