For Modeling Nonlinear Material Models in Geomechanics
Simulate Your Geotechnical Applications
As an add-on to the Structural Mechanics Module, the Geomechanics Module allows you to analyze geotechnical applications, such as tunnels, excavations, slope stability, and retaining structures. Utilizing a number of nonlinear geomechanics material models, it contains tailor-made physics Interfaces for investigating deformation, plasticity, creep, and failure of soils and rocks, and their interactions with piles, supports, and other manufactured structures.
A Variety of Geomechanics Material Models for Great Versatility
The Geomechanics Module comes with standard nonlinear material models that describe metal plasticity through the von Mises and Tresca criteria. Yet, the essence of the Geomechanics Module is the nonlinear material models for soils, concrete, and rock that are built into physics interfaces modeling solid mechanics.
|Soils||Rock and Concrete|
- Embankments are used to support a road embankment. Shown are the stresses in the columns and displacement of the surrounding environment (background boundary surface plot).
- Force is transferred from a concrete beam to its steel reinforcement bars during tension failure. Shown are the von Mises stresses in the concrete and the axial stresses in the bars.
- Large strain plastic deformation where a tension cut-off criterion has been set.
In addition to the pre-defined, built-in plasticity models, you can create user-defined yield functions. These can be created either directly, by manipulating the physics interfaces in the Geomechanics Module, or through the versatile equation-defining physics interface found in COMSOL Multiphysics. User-coded subroutines are not required, as you may simply enter the constitutive equations in the appropriate edit field within the interfaces. These can involve mathematical expressions of the field variables, stress and strain invariants, and derived quantities. If your material model is dependent on another variable, such as a computed temperature field or water pressure, you can directly integrate it into these material definitions. In this way, the provided material models within the Geomechanics Module can also be adapted and extended to a more general class of materials.
The Geomechanics Module can easily be combined with analyses and their describing variables from other modules in the COMSOL Product Suite. This includes, in particular, physics interfaces describing porous media flow, poroelasticity, and solute transport featured in the Subsurface Flow Module.
Concrete Beam with Reinforcement Bars
Concrete structures almost always contain reinforcements in the shape of steel bars ("rebars"). In COMSOL, individual rebars can be modeled by adding a Truss interface to the Solid interface used for the concrete. The solid mesh for the concrete and the rebar mesh can be independent, since the displacements are mapped from within the solids onto ...
This deep excavation model is inspired by a benchmark exercise specified by a working group of the German Society for Geotechnics. In this model, a 20 m excavation is modeled with ten steps by means of a parametric sweep. The interaction between the soil and the retaining wall is modeled with contact pairs, and struts are activated as the ...
This model provides an estimation of the behavior of the soil during a tunnel excavation. The surface settlement and the width of the plastic region around the tunnel are important parameters needed to predict the reinforcements to use during the excavation. Two study steps are used. The first computes the stress state of the soil before ...
The triaxial test is one of the most common tests used in laboratory soil testing. The soil sample is normally placed inside a rubber membrane and then compressed maintaining a radial pressure. In this model, a vertical displacement and a confinement pressure are applied on the sample and the static response and the collapse load for various ...
Flexible and Smooth Strip Footing on a Stratum of Clay
A common verification model for geotechnical problems is of a shallow stratum layer of clay. In this model, a vertical load is applied to the clay strata top surface and the static response and collapse load are studied. The clay is modeled as an elastic-perfectly plastic material and the Mohr-Coulomb yield condition under plane strain ...
This model shows how to set up a uniaxial compression test on a prestressed soil sample. Due to uniaxial compression and simple initial stress values, it is possible to determine the vertical yield stress analytically. The soil sample is modeled with soil plasticity and the Mohr-Coulomb criterion.
Isotropic Compression Using Cam-Clay Model
Isotropic compression is a common exercise in soil testing. The modified Cam-Clay model describes the relation between the void ratio and the logarithm of the pressure. In this example, a soil sample is placed inside cylinder 10 cm in diameter and 10 cm in height. Due to the symmetry, the model is solved in 2D axial symmetry. A boundary load ...