Examine 2D 8.0 is here!

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1 Examine 2D 8.0 is here! Rocscience is pleased to announce the release of Examine 2D version 8.0, an upgrade to our very popular FREE stress analysis program. Examine 2D uses the boundary element method for calculating elastic stresses and displacements around underground and surface excavations in rock. Unlike the finite element method, the boundary element method only requires discretization on the excavation boundaries, eliminating the need for complex volume mesh generation. Hence the analysis compute time is almost instantaneous. Model geometry and input parameters can be varied and output results are updated and displayed in real time, allowing you to interactively view the effects of different modeling scenarios as input parameters are changed. This article highlights the primary new features in Examine 2D 8.0: Joint Boundaries can be used to model joints or faults in a rockmass User Data user defined data types can now be plotted and contoured

2 Joint Boundaries The primary new feature in Examine 2D 8.0 is the ability to model joints, faults or other discontinuities with the Add Joint option. Joints in Examine 2D are modeled using displacement discontinuity elements (DDs) which allow shear displacement (slip) and opening or closing (normal displacement) along the joint. Joints are added/edited in the same manner as other boundary types. There is no limit on the number of joint boundaries, and they can intersect excavations, ground surface or other joints. Multiple joint boundaries around horseshoe tunnel

3 Joint Properties Joint properties are entered in the Examine 2D sidebar. Joints can be defined as elastic (only normal and shear stiffness parameters required); in addition you may assign strength properties to joints using either Mohr-Coulomb or Barton- Bandis slip criterion. If the shear stress on a joint element exceeds the strength criterion then slip may occur on the joint element. Elastic joint properties Mohr-Coulomb joint properties Barton-Bandis joint properties Analysis results are instantly updated as you change the input parameters, allowing you to easily carry out an interactive sensitivity analysis to determine the effect of individual input parameters on joint and rock mass behaviour. If multiple joint boundaries are defined, the same joint properties apply to all joint boundaries in the model.

4 Joint Analysis Results A variety of options are available for the display of joint analysis results. You can plot joint data directly on the model Generate a graph of joint data Plot joint yielding and slip direction Define user data for joints To view analysis results for a joint, you can use the Query Boundary option to create a query along the joint. You will then be asked to choose the data you would like to plot as shown in the dialog below. Joint data types available for plotting Choose the desired data type and select OK, and the data will be plotted along the joint. Note that the Current Grid Data option (see above figure) allows you to plot the currently selected rock mass data (e.g. Sigma 1) along the joint boundary. The display of the joint data can be customized in the Display Options dialog. In the following figures: the shear displacement is plotted along a horizontal joint above a circular tunnel you can easily generate a graph of joint data, and export the results to Excel for further processing joint yielding (slip) and slip direction is highlighted.

5 Shear displacement along joint over circular tunnel Graph of shear displacement along joint

6 Joint shear data and graph exported to Excel with one mouse click Joint slip (red) and slip direction (arrows) highlighted on joint boundary

7 User Data Rock Mass Another useful new addition to Examine 2D is the ability to define and plot user-defined variables. The Rock Mass User Data option in the Analysis menu allows you to create userdefined rock mass variables which can be contoured and plotted. You can plot: any stress component any strain component strength properties elastic properties or write a mathematical expression containing these components, and view the results of this function. To plot user data you must first define user data variables using the dialog shown below. When Rock Mass User Data variables have been defined, they will appear at the end of the list of analysis variables in the toolbar. They can then be selected like any other data type (e.g. Sigma 1, Strength Factor etc), and a contour plot of the selected User Data will be generated.

8 User Data Joints User Data can also be defined for joints using the Joint User Data option. The Joint User Data option works in the same way as described for the Rock Mass User Data option. You can create user-defined variables for joint data. The user-defined variables will then appear in the list of available joint data when you plot and graph queries for joint boundaries.

9 Examine 2D Comparison with Phase 2 The behaviour of joints in Examine 2D has been compared with equivalent models created in the finite element program Phase 2. It was verified that for equivalent models, joint boundaries in Examine 2D and Phase 2 give virtually identical results as shown in the example below. Joint boundary and cavern model in Examine 2D Joint boundary and cavern model in Phase 2 Notice that the rock mass stress contours and joint yielding (red highlight) are virtually identical in the two models. The Phase 2 model uses infinite elements on the external boundary to match the boundary conditions of Examine 2D.

10 Keep in mind that Examine 2D is still primarily a quick and easy to use elastic stress analysis tool. For full featured finite element modeling including multiple materials, staging, plasticity, groundwater and support, you will need to use Phase 2. Summary The new joint modeling and analysis features of Examine 2D 8.0 are a welcome addition to the geotechnical software suite offered by Rocscience. For a complete listing of all new features in Examine 2D 8.0 see: What s New in Examine 2D 8.0 Examine 2D continues to be offered as a free download from the Rocscience website. You may request your free version of Examine 2D v8.0 from: Don t forget to try out our free program RocLab as well. For a full featured version of RocLab see RocData.