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Intel software, Wolfram Mathematica, Origin, Statgraphics, EViews
Intel software, Wolfram Mathematica, Origin, Statgraphics, EViews
Info e Commerciali Intel software, Wolfram Mathematica, Origin, Statgraphics, EViews
SIGMA/W 2019
Lingua: Ing S.O.: Win
Produttore: GeoSlope
  ADALTA è Importatore Unico e Distributore Ufficiale per l'Italia per i prodotti GeoSlope


SIGMA/W

 

Stress and deformation analysis

SIGMA/W is a powerful finite element software product for modeling stress and deformation in earth and structural materials. SIGMA/W analyses may range from simple linear elastic simulations to soil-structure interaction problems with nonlinear material models.

Many constitutive soil models enable you to represent a wide range of soils or structural materials. In addition, SIGMA/W models pore-water pressure generation and dissipation in response to external loads. With SIGMA/W you can analyze almost any stress or deformation problem you will encounter.

Key Features

Construction Sequence

GeoStudio's Analysis Tree models even the most complex construction sequences. Analyses are added to the Tree, forming a Parent-Child relationship in which each new analysis represents a part of the construction sequence. 

Coupled Consolidation

The coupled stress and pore-water pressure formulation can be used to model construction sequencing involving fill placement, excavation, and soil-structure interaction.

SLOPE/W Integration

The stresses and/or pore-water pressures from a SIGMA/W analysis can be used directly in SLOPE/W to do a stress-based stability analysis. 

Stress Redistribution

Stress redistribution analysis is used to conduct a strength reduction slope stability analysis, model stress transfer onto structures such as pile walls installed within failed slopes, or calculate permanent deformations.

SIGMA/W can model almost any stress or deformation problem

Download GeoStudio to view GSZ files

Bangkok Wick Drain

Before construction of a new airport in Bangkok, Thailand, full-scale test embankments were constructed on the site to study the effectiveness of prefabricated vertical drains (PVDs) for accelerating the consolidation and dissipation of the excess pore-pressures resulting from fill placement.

Download the GeoStudio data files(1) (2) (3)

Read the analysis details

Cubzac-les-Ponts, France

In the 1970's, a series of test embankments were constructed on soft clay at Cubzac-les-Ponts in France. These full-scale field tests were well-instrumented and are well-documented, and consequently provide an excellent case history. Two of the embankments are the subject of this article.


Download the GeoStudio data files (1) (2)

Read the analysis details

Excavation Below Watertable

The primary objective of this example is to consider the change in pore-water pressure during an excavation below the watertable, particularly the potential for negative pore-water pressures to form. A secondary objective of the example is to demonstrate the use of a moving hydraulic boundary condition on the excavation face.

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Read the analysis details

Braced Deep Excavation

Halim and Wong's paper in Underground Singapore 2005 presents six case histories where deflections of the shoring walls were measured during construction. The case histories show that GeoStudio has the capabilities to model the behavior of deep shored excavations in soft ground.

Download the GeoStudio data files
Read the analysis details

SIGMA/W's intuitive modeling workflow

Create a SIGMA/W analysis and set up the problem workspace. Choose the analysis type, such as Insitu stress, stress redistribution, load/deformation, coupled stress/pore-water pressure, volume change, and dynamic deformation.

Draw the regions in your domain using CAD-like drawing tools, including drawing polygon and circular regions, coordinate import, copy-paste geometric items, length and angle feedback, region splitting and merging, and direct keyboard entry of coordinates, lengths, and angles. Alternatively, import AutoCAD DWG or DXF files directly into GeoStudio to create your domain geometry.

Define the material properties for your analysis, assign them to regions on the domain, and then define your initial pore-water pressure conditions. Define materials using total stress parameters, effective drained parameters or effective parameters with pore-water pressure changes included. Define the initial pore-water pressure conditions for transient scenarios using results from other SEEP/W or SIGMA/W analyses, defined spatial functions or draw an initial water table.

Define stress/strain boundary conditions to simulate stress and fluid pressure conditions or displacement/force conditions to be placed on the domain. Hydraulic boundary conditions can also be added to simulate total head, pressure head, pore-water pressure, water flux (q), water rate (Q), and climatic conditions. Time-varying loading and hydraulic functions can be defined to simulate changing conditions over the duration of a transient analysis. Structural beams and bars can also be applied to the model domain.

Open Draw Mesh Properties to refine the mesh drawn on the entire domain, or along specific geometric regions, lines or boundaries. Interface elements can also be created to simulate frictional properties between materials or between a soil and a structure.

When your problem is completely defined, start the analysis process in the Solve Manager window. The Solve Manager displays the solution progress, allowing you to cancel or stop/restart if necessary. While the solution is in progress, you can look at preliminary results in the Results window.

When the Solver is finished, the Y-total stress contours are displayed, with displacement results displayed as either a deformed mesh or vector arrows. Many other contour options are available in the Draw Contours window, including pore-water pressure, material properties, water flow, and gradients. Contour legends and properties can also be modified. Labels can be added to contour lines in Results View. Liquefaction zones following an earthquake can also be displayed.

Interactively select any node or gauss region to view result information, including resulting displacement, pore-water pressure, material properties, and more. Draw Mohr Circles to review the stress/strain state of any node or gauss region. Display plots of computed results over the x- or y-direction or create time-varying plots of results in transient analyses, such as displacements, pore-water pressure, total or effective stresses, and more. Generate reports of the definition and results, and export into other applications such as Microsoft Excel for further analysis.

 

Complete Feature List
 

Integrated into the GeoStudio Suite

SIGMA/W is integrated into the GeoStudio suite, and therefore has access to the GeoStudio features for creating your model, analyzing it, and viewing results.


Comprehensive Stress-Strain Formulation

SIGMA/W uses a finite element-based formulation for performing stress and deformation analyses of earth structures. Its comprehensive stress-strain formulation makes it possible to analyze both simple and highly complex problems. SIGMA/W can perform a simple linear elastic deformation analysis or a highly sophisticated, nonlinear elastic-plastic effective stress analysis, which may involve soil-structure interactions, coupled stress and pore-water pressure response, and stress-based stability considerations. The many constitutive soil models allow you to represent a wide range of soils or structural materials. In addition, SIGMA/W can model the pore-water pressure generation and dissipation in a soil structure in response to external loads. These features enable SIGMA/W to analyze almost any stress or deformation problem you will encounter in geotechnical, civil, and mining engineering projects.


Incremental Load Formulation

SIGMA/W is formulated for 1 or 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 finite elements at various stages of the construction process.


Typical Applications

SIGMA/W can model almost any stress/deformation problem, including:

  • Settlement of footings, fluid-filled tanks, or earth structures
  • Deformation within or underneath an embankment or earth dam
  • Lateral movement of braced or anchored excavations and surface settlement around the excavation
  • Floor rebound of open-pit and sloping excavations
  • Volume change resulting from pore water pressure change
  • Staged fill placement and excavation
  • Soil-structure interactions, including anchors, struts, and trusses
  • Fully-coupled consolidation analysis
  • Tailings deposition 
  • Permanent deformations resulting from strength loss
  • Strength reduction stability
  • Subsurface drainage design for soft soils
  • Closure around a tunnel and stresses in the tunnel lining

Obtain Converged Solutions for Challenging Problems

SIGMA/W implements a rigorous stress redistribution algorithm that is capable of handling the most challenging non-linear stress-strain material models.


Saturated-Unsaturated Formulation

SIGMA/W is formulated to handle both saturated and unsaturated soils, which provides greater flexibility for handling coupled engineering problems.


Coupled Consolidation Analysis

The coupled stress and pore-water pressure formulation can be used to model construction sequencing involving fill placement, excavation, and soil-structure interaction. The rigorous formulation simulates the instantaneous changes in pore-water pressure associated with a change in stress, followed by the subsequent time-dependent dissipation or recovery of pore-water pressures and the associated deformations.


Model Construction Sequences with Ease

The Analysis Tree in GeoStudio provides a powerful and simple way to model even the most complex construction sequence. Analyses are added to the Tree, forming a Parent-Child relationship in which each new analysis represents a part of the construction sequence and forms the initial condition for the subsequent construction activities.


In situ Condition Options

In situ stresses can be established using either Poisson's ratio or by specifying an initial K 0 value for the material. This provides the ability to model heavily over-consolidated soils in which the horizontal stresses exceed the vertical.


Comprehensive Constitutive Model List

SIGMA/W offers a comprehensive list of constitutive models including Linear-Elastic, Anisotropic Linear-Elastic, Elastic-Plastic Mohr-Coulomb, Hyperbolic, Modified Cam-Clay, and the add-in functionality common to all GeoStudio products. An add-in can be used to incorporate your own types of constitutive behaviour, such as elastic viscoplasticity.


Total and Effective Stress Material Categories

The ability to use total stress, effective stress, or coupled material models simultaneously in all analysis types, creates significant flexibility for modeling real-world engineering problems.


Estimate Material Properties for Typical Materials

Material properties, such as the E-Modulus versus Stress function, can be estimated using built-in properties for typical materials. The estimation process requires only fundamental material information such as the soil classification.


Comprehensive Range of Generalized Boundary Conditions

SIGMA/W supports a comprehensive list of boundary condition options including normal/tangential stress, X-Y stress, hydrostatic pressure, displacement, force, or spring boundaries. In keeping with the entire GeoStudio suite, SIGMA/W makes broad use of generalized functions for boundary condition definition. As such, actual field data over time or user-specified functional relationships can be pasted into SIGMA/W. SIGMA/W also allows zero-rotation boundary conditions to be used on structural components.


Hydrostatic Stress Boundary for Water Surcharge Loads

The hydrostatic stress boundary provides a convenient approach for modelling the water surcharge load in either an in situ analysis or a transient coupled stress and pore-water pressure analysis. This makes it possible to model problems such as rapid drawdown in a single analysis.


Soil-Structure Interaction

SIGMA/W's structural elements can be used to model anchors, nails, tie-backs, wall systems, piles or any other soil-structure interaction problem in geotechnical engineering.


Integrated with SLOPE/W for Stress-Based Stability Analyses

The stresses and/or pore-water pressures from a SIGMA/W analysis can be used directly in SLOPE/W to do a stress-based stability analysis.


Stress Redistribution Analysis

The stress redistribution analysis can be used to conduct a strength reduction slope stability analysis, model stress transfer onto structures such as pile walls installed within failed slopes, or calculate permanent deformations resulting from strength loss due to liquefaction or strain softening.


Model in 1D, 2D or Axisymmetric View

SIGMA/W includes analysis options for modeling pseudo three-dimensional problems.


Powerful Graphing Options

Graphing is critical for the interpretation of stress-strain problems. The powerful graphing options in GeoStudio make it possible to plot critical information such as lateral displacement, surface settlements, pore-water pressure versus time, bending moments, shear distribution in structures, and more. All of this data can be exported or copy/pasted directly into spreadsheet software.


View Stresses in a Mohr Circle

A Mohr Circle can be plotted at any gauss point or node to further interrogate the results.


View Deformed Mesh and Yield Zone

Interpretation of the results is enhanced through the ability to view a deformed mesh, displacement vectors, and the location of the yield zone.


Sensitivity Analysis with SIGMA/W

A sensitivity analysis can be readily conducted with SIGMA/W by cloning multiple analyses using the Analysis Tree and then making slight changes to each one.


 




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