Research methods

Stand: 24.11.2024

Experimental soil mechanics

  • Laboratory tests

    • Classification tests

      • Determination of grain size distribution according to DIN EN ISO 17892-4 (formerly DIN 18123)
      • Determination of water content according to DIN EN ISO 17892-1 (formerly DIN 18121)
      • Determination of Atterberg limits for cohesive soils according to DIN EN ISO 17892-12 (formerly DIN 18122)
      • Determination of density according to DIN EN ISO 17892-2 (formerly DIN 18125)
      • Determination of bulk density according to DIN EN ISO 17892-3 (formerly DIN 18124)
      • Determination of emin and emax for non-cohesive soils according to DIN 18126
      • Determination of lime content according to DIN 18129
      • Determination of ignition loss according to DIN 18128
      • Determination of water absorption capacity according to DIN 18132
      • Determination of hydraulic conductivity according to DIN ISO/TS 17892-11V (formerly DIN 18130)
      • Determination of Proctor density and optimal water content according to DIN 18127
      • Determination of angle of repose of non-cohesive soils
      • Determination of abrasivity with the abrasimeter according to ANFOR NF P 18-579
      • Determination of properties of suspensions (suspension density, run-out time with the Marsh funnel, spread dimension, yield limit using spherical harp, filtrate water discharge, settling dimension in the stand cylinder)
      • Determination of viscosity of fluids with the rheometer

    • Permeability tests

      • Permeability test with constant head
      • Permeability test with falling head

    • Investigation of stress-strain behaviour

      • Oedometer tests (IL, CRS, creep test, swelling test, soft oedometer test)
      • Direct shear tests (constant normal stress, constant volume, constant stiffness, monotonous/cyclic loading)
      • Ring shear tests
      • Triaxial tests including standard tests (CD, CU, UU) and a couple of special tests
      • Uniaxial compression test
      • Simple shear tests (monotonous/cyclic loading, constant normal stress, constant volume or constant stiffness, multiaxial shear test with continuous change of shear direction, investigation of capillarity in unsaturated soils)
      • Resonant-Column Test
      • Laboratory vane shear test

    • Determination of capillary-saturation behaviour

      ...

    • Imaging methods

      • Optical microscopy
      • Computed Tomography (CT)
      • ...

  • Physical Modelling (model tests)

    • 1g model tests
    • ng model tests (centrifuge tests) in cooperation with the Centre of Offshore Foundation Systems (COFS) at University of Western Australia (UWA) in Perth
    • Field tests in on a semi-industrial and prototype scale

  • Field tests

    • Measurement of displacements, strains, forces, stresses, velocities, accelerations etc.
    • Measurement of dispersion waves

Theoretical soil mechanics

  • Multiphase-models for saturated and unsaturated soils based on continuum theories for porous media
  • Development of a constitutive model for the transition of soil → concrete, required in the course of numerical optimization
  • Investigation of capillarity in unsaturated soils

Computational soil mechanics

  • Continuum models (macroscopic approach)

    • Governing equations: Terzaghi's consolidation theory and extensions, Biot's poroelasticity and derived poroplasticity (poromechanics), mixture theories
    • Numerical Methods:
      • Finite Element Method (FEM) with Lagrangian approach for small to moderate soil deformation
      • Finite Element Method (FEM) with Coupled Eulerian-Lagrangian (CEL) approach for large soil deformation
      • Smoothed Particle Hydrodynamics (SPH) for large soil deformation and for separation of soil constituents
      • Material Point Method (MPM) for large soil deformation

    • Calibration of constitutive models for soils

  • Particle models (microscopic approach)

    • Governing equations: Newton's equation of motion
    • Numerical Method: Discrete Element Method (DEM)

  • Models based on Boltzmann's kinetic theory (mesoscopic approach)

    • Governing equation: Boltzmann equation
    • Numerical method: Lattice-Boltzmann Method (LBM)

  • Hybrid models (multiscale approaches)

    • Multiscale models for saturated soils based on a continuum model for the pore fluid and a particle model for the grain skeleton
      • Governing equations: Field equations for the pore fluid, Newton's equations of motion for the particles, model for the momentum exchange between pore fluid and particles
      • Numerical methods: CFD-DEM coupling resolved (several fluid cells per particle), CFD-DEM coupling unresolved (several particles per fluid cell)

    • Multiscale models based on Boltzmann's kinetic theory for the pore fluid and particle mechanics for the grain skeleton:
      • Governing equations: Boltzmann-equation for the pore fluid including a collision model, Newton's equation of motion for the particles, and a model to describe the momentum exchange between pore fluid and particles
      • Numerical method: LBM-DEM coupling in cooperation with Prof. Krishna Kumar

Numerical optimization

  • Numerical multi-criteria optimization in combination with numerical simulation

Conventional calculation methods

  • For example. Kinematic Element Method (KEM), slope stability analysis etc.