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OptumG2 allows for an easy and intuitive modelling of geometry with automatic recognition of intersections, closed surfaces, etc. Solid modelling tools include Move, Copy, Paste, Scale, and Rotate. Coordinates and other geometric data may be entered either by mouse click or via the keyboard.
Special features facilitating an accurate and convenient modelling include special elements for modelling walls, anchors, geotextiles, interfaces and joints.
Finite Element Technology
OptumG2 contains a range of finite elements including the popular 6-node and 15-node triangles. In addition, elements that allow for the rigorous assessment of upper and lower bounds on quantities of interest are available.
Geometries modeled in external CAD applications can easily be imported via DXF files.
OptumG2 includes models of different degrees of complexity, each with particular strengths for particular types of geomaterials. As a minimum, a typical material involves strength and stiffness properties. In addition, a number of features are common to all materials. These include unit weight, earth pressure coefficient and hydraulic properties. Finally, a number of useful enhancements have been included into many of the models, for example tension cut-offs, compression caps, and embedded fissures. A brief overview of the material models available in OptumG2 is given below.
This is the most widely used constitutive model for geomaterials. The advanced implementation in OptumG2 makes for an unsurpassed robustness. Difficult problems that often lead to failure in conventional programs are handled in a reliable and straightforward manner. The advantages are particularly pronounced in the modelling of sands (zero cohesion, large friction angles and small dilation angles).
This is another basic model for geomaterials. It is similar to the Mohr-Coulomb model and is implemented along the same lines, ensuring maximum efficiency and robustness of the calculations.
This model allows for direct input of undrained strength and/or stiffness parameters and is a useful alternative to the Mohr-Coulomb model in cases where only the undrained properties are available.
The Hoek-Brown failure criterion is commonly used for fractured rock. In OptumG2, this failure criterion forms the basis of the Hoek-Brown elastoplastic model which operates under the assumption of linear elasticity up to the point of failure. The flow rule can be either associated or nonassociated (with or without dilation cap) and a hardening compression cap can be included to model the effects of very large hydrostatic stresses.
The GSK model is similar to the Mohr-Coulomb model, but involves a nonlinear relation between the normal and shear stresses at failure. It is suitable for clays, sands under low confining pressures, and various types of rock and sandstone.
Modified Cam Clay
This is a classic model for soft clays and has been widely used in a large number of different scenarios. The unique and innovative implementation used in OptumG2 ensures a high level of computational efficiency and robustness.
The Extended Mohr-Coulomb model is an advanced hardening soil model. However, the input is in the form of familiar quantities such as the secant Young’s modulus (E50), Mohr-Coulomb friction angle, and similar. The model is particularly suited for deformation analysis of problems where both loading and unloading occurs, e.g. excavations. Its strength properties coincide with those of the standard Mohr-Coulomb model.
The Rigid material has infinite stiffness (zero compliance) and infinite strength. This material is useful for the modelling of foundations and other structural elements that are much stiffer and stronger than the surrounding soil.
Fluids are a class of materials similar to solids. They are useful in the modelling of water bodies and avoid the need to apply additional boundary conditions to account for the presence of water pressures.
Plates, Geogrids, Connectors, and Hinges
Material models for various elastic, elastoplastic, and rigid structural elements are available.
OptumG2 is a finite element program for strength and deformation analysis of geotechnical boundary value problems. It has a number of overall principles in common with other programs available on the market, but also differs fundamentally on a number of points. For example, it is possible to compute failure loads directly without having to perform a traditional step-by-step elastoplastic analysis. Moreover, it is possible to compute rigorous upper and lower bounds to the failure load, thus bracketing the exact solution from above and below. Conversely, given a set of fixed loads, it is possible to compute upper and lower bounds on the exact strength reduction factor, i.e. the factor by which the material strengths need to be reduced in order to cause collapse. The analysis types available in OptumG2 are:
Traditional finite element deformation analyses accounting for a variety of material models and boundary conditions, including development of plasticity, seepage, and consolidation. Can be performed for a final construction state or various states to attain full deformations throughout construction or changing stress conditions.
The Strength Reduction analysis in OptumG2 proceeds by computing a strength reduction factor by which the material parameters need to be reduced in order to attain a state of incipient collapse. The resulting factor may be interpreted as the factor of safety against collapse.
This analysis performs seepage analysis in accordance with the material properties and seepage boundary conditions. No distinction is made between confined and unconfined seepage and both are treated within a general variably saturated framework.
Limit Analysis is one of the core analysis types of OptumG2. It allows for a rapid assessment of the stability or bearing capacity of geostructures without having to perform an exhaustive step-by-step elastoplastic analysis.
The initial stresses in the ground are in many cases an important aspect of strength and deformation analysis. The Initial Stress Analysis determines the stress field that satisfies the equilibrium, boundary conditions, yield conditions and earth pressure conditions. This analysis type is unique to OptumG2.
This analysis type is atypical in that it does not involve physics. Moreover, for all physical analyses, the mesh is generated automatically and does not have to be constructed by the user.
OptumG2 contains a variety of tools for visualizing the results. All computed quantities (displacements, stresses, strains, etc) may be displayed as color distributions on the background mesh. In addition, movies visualizing the deformation process may be played either within OptumG2 or may be recorded for external viewing using standard movie players.
A report containing all relevant information may be generated automatically. A high degree of customization is possible. For example, result plots are easily added to or removed from the report by the user.
An analysis log provides you with temporary results, state of your analysis, warnings etc. on the fly.
All results, e.g. displacements, stresses and strains, may be exported to a user friendly format for possible processing and visualization via third-party programs.