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Analysis Options
The Project Settings dialog is used to configure the main analysis options in Examine2D:
Analysis options in Project Settings dialog
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Analysis Options: Units
An Examine2D model can be defined using a variety of metric or imperial unit conventions. The units are defined by selecting the unit of stress measurement:
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Metric stress units: MPa, kPa, tonnes/m2
Imperial stress units: ksf, psf, tons/ft2
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The units of all input parameters (e.g. length, force, unit weight) and analysis results are determined by the selected stress measurement unit.
For more information see the Unit System topic.
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Analysis Options: Field Stress
The Field Stress defines the in situ stress state in the ground prior to excavation. In Examine2D there are two options for defining the Field Stress:
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Constant
Gravitational
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The Constant option assumes that the in situ stress magnitude is constant (used for deep excavations), while the Gravitational option assumes that the in situ stress varies linearly with depth from the ground surface (used for surface or near surface excavations).
For more information see the Field Stress topic.
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Analysis Options: Material Properties
The Examine2D stress analysis is elastic and assumes a single homogeneous material. The elastic and strength properties of the material (i.e. rock or soil) are required in order to compute stresses, displacements and strength factor around the excavation.
The elastic property options are:
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Isotropic
Transversely Isotropic
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The strength criterion options are:
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Mohr-Coulomb
Generalized Hoek-Brown (use GSI, mi, D or mb, s, a)
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For more information see the Material Properties topic.
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Analysis Options: Analysis Type
Plane Strain analysis assumes that the strain normal to the analysis section is zero. There are two Plane Strain analysis options available in Examine2D:
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Plane Strain
Complete Plane Strain
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For Plane Strain, it is assumed that one of the in situ principal stresses is aligned with the axis of the excavation, therefore the stress analysis results are in terms of in-plane and out-of-plane stresses. For Complete Plane Strain, the in situ stress field can be arbitrarily oriented with respect to the excavation axis, therefore the stress analysis results are 3-dimensional.
For more information see the Analysis Type topic.
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Analysis Options: Boundary Elements
In a boundary element analysis, the model boundaries are discretized into smaller segments (i.e. the boundary elements). This discretization is automatically performed by Examine2D, however, the user can specify:
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Number of Boundary Elements
Boundary Element Type
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The default settings generally give good results. Accuracy of the analysis results may improve if you increase the number of elements, or use higher order elements (e.g. linear or quadratic); however the computation time will increase accordingly.
For more information see the Boundary Elements topic.
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Analysis Options: Matrix Solver
The matrix solver is used to solve the system of equations which represent your model. There are two options available:
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Jacobi Bi-Conjugate Gradient
Gaussian Elimination
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By default, Examine2D uses the Jacobi Bi-Conjugate Gradient method, an iterative solver which is very efficient for large matrices. Matrix size is dependent on the number of boundary elements and the element type (constant, linear, quadratic).
For more information see the Matrix Solver topic.
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