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Material Properties
The Examine2D stress analysis requires the Elastic and Strength properties of the rock mass. The elastic type and strength type are selected in the Project Settings dialog, and the properties are then entered in the Sidebar.
Elastic and strength options in Project Settings
Although Examine2D is primarily for the analysis of excavations in rock, it can be used for soil applications. Therefore the material properties can represent either rock mass or soil properties.
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Material Properties: Elastic
The following elastic models are available in Examine2D:
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Isotropic
Transversely Isotropic
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An Isotropic material implies that the material properties do not vary with direction. The elastic properties of an Isotropic material are fully defined by a single value of Young's Modulus (Em), and a single value of Poisson's Ratio.
Isotropic Elastic Properties
A Transversely Isotropic material has properties which vary with direction, in the plane of the analysis. The elastic properties are specified in orthogonal directions, and an angle defines the orientation of the properties with respect to the x-axis.
Transversely Isotropic Elastic Properties
For more information see the Elastic Properties help topic.
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Material Properties: Strength Criterion
In Examine2D you can choose one of the following strength criteria:
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Mohr-Coulomb
Generalized Hoek-Brown
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NOTE: Strength Properties in Examine2D are ONLY USED to compute the Strength Factor contours (i.e. degree of overstress, based on the elastic stress distribution). Plasticity and stress re-distribution due to failure cannot be modeled in the Examine2D boundary element analysis. If you want to model progressive failure (i.e. plastic analysis) then use the finite element program Phase2.
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The Mohr-Coulomb criterion is applicable for either rock or soil. If you are using the Mohr-Coulomb criterion for rock, then your input parameters should represent the strength of the rock mass, not the intact rock properties.
Mohr-Coulomb strength parameters
The Generalized Hoek-Brown strength criterion is used for modeling rock mass strength. The strength parameters can be defined in two ways:
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By directly entering the strength criterion parameters mb, s and a (and
intact UCS)
By entering the parameters GSI, mi and D (and intact UCS), from which mb,
s and a are automatically calculated.
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For more information see the Strength Properties help topic.
Generalized Hoek-Brown parameters (mb, s, a)
Generalized Hoek-Brown parameters (GSI, mi, D)
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Material Properties: Estimating Input Parameters
If you are using the Generalized Hoek-Brown strength criterion (GSI, mi, D), the input parameters can be estimated using convenient charts and tables, by selecting the Pick button:
located beside the input edit boxes in the Sidebar. A table or chart will appear, allowing you to estimate a value for the parameter. For example, the dialogs for estimation of mi and GSI (Rock Type = General) are shown below.
Dialog for estimation of mi value
GSI chart (Rock Type = General)
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