Joel Given

Joel is a Ph.D. student at UC Berkeley within Prof. Kenichi Soga’s computational geomechanics group. Joel’s research currently focuses on two main areas:

1. applying the Material Point Method (MPM) to solve geotechnical problems that produce large deformations and/or require high accuracy stress-strain calculations, and
2. improving soil constitutive models.

MPM

MPM modeling is completed with a single-phase explicit code; both standard and cut-mesh MPM algorithms are used to calculate near cavity stress-strain behavior. The high accuracy stress-strain calculations are used to model the cavity erosion using a plastic strain removal rule. The total quantity of removed mass is particularly sensitive to changes in removal rule parameters; extensive sensitivity studies have been completed.

Modeling cavity erosion as isotropic external load increases; colorbar represents development of equivalent-plastic-deviatoric strain that comprises a portion of the erosion rule.

Changing removal rule parameters has a significant effect on the quantity and rate of removed material mass.

Constitutive Modeling

Past constitutive modeling work includes combining the Bonded NorSand formulation from Material Point Method for Large Deformation Modeling in Geomechanics Using Isoparametric Elements (Setiasabda, 2020) with an updated formulation of the NorSand yield surface from Soil Liquefaction, a Critical State Approach (Jefferies & Been, 2019).

Ongoing constitutive modeling work involves the addition of elastic anisotropy to advanced soil models (e.g., Bonded NorSand); anisotropic stiffness is one approach to capture the effects of soil fabric on overall behavior.

Links:

CB-Geo MPM Code https://github.com/cb-geo/mpm