Formulation
SIGMA/W is formulated for 2-dimensional plane strain or axisymmetric problems using a small displacement, small strain, incremental load formulation. For each load step, incremental displacement at each node resulting from the incremental load is computed and added to the displacement at the beginning of the load step to give the total displacement. For soil models with nonlinear material properties, SIGMA/W solves the equations iteratively using the Newton-Raphson technique; soil properties are updated every iteration until a converged solution is achieved.
You can simulate the filling and excavation of materials by activating or deactivating regions at various stages of the construction process. SIGMA/W can be used with SEEP/W for uncoupled consolidation analyses. SEEP/W calculates transient pore-water pressure changes due to the applied load, while SIGMA/W calculates deformations resulting from the pore-water pressure changes.
Features
Analysis types include drained total and effective stress, undrained total and effective stress, 2D plane strain, 3D axisymmetric, consolidation and swelling, and insitu stress.
Constitutive soil models include linear-elastic, anisotropic linear-elastic, elastic-plastic, and Modified Cam-clay.
Boundary condition types include X and Y displacements, forces, pressures, and spring constants, as well as self-weight gravity loading.
Structural beam and bar elements for soil-structure interaction.
Staged loading for fill placement or earth removal.
Uncoupled volume change due to pore-pressure changes.
Fully-coupled stress-pore pressure analyses.
User-defined Add-In constitutive models.
Integration with Other Applications
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Product Integration Chart
GeoStudio Product Integration Chart
Use SIGMA/W stresses in SLOPE/W or QUAKE/W
Using finite element computed stresses in SLOPE/W makes it possible to conduct a rigorous stability analysis using the same stress values resulting from the deformation analysis. In addition, you can use SIGMA/W stresses as the initial stress state for a dynamic earthquake analysis in QUAKE/W.
Use SIGMA/W pore-water pressures in SLOPE/W or SEEP/W
Excess pore-water pressures generated by static loading, such as fill placement, can be brought into SEEP/W to study how long it takes to dissipate the excess pressures in the foundation. You can use SLOPE/W to analyze the effect of these excess pressures on stability during construction, allowing you to determine the need for staged loading.
Engineering Methodology Book
Stress-Deformation Modeling with SIGMA/W The included SIGMA/W engineering methodology book discusses the whys and hows of modeling, as well as the theory and formulations behind the SIGMA/W product. Stress-Deformation Modeling with SIGMA/W is a full-length book about proper modeling techniques: how to think before, during and after setting up and solving a model. The book includes chapters devoted to:
Numerical Modeling: What, Why and How
Fundamentals and Practical Modeling Considerations
Geometry and Meshing
Material Models and Properties
Bounday Conditions
Analysis Types
Coupled Stress-Pore Pressure Analysis
Functions in GeoStudio
Structural Elements
Staged Construction Sequencing
Numerical Issues
Visualization of Results
Illustrative Examples
Theory