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Steps for a Typical Deterministic Analysis

In a Deterministic Analysis, it is assumed that all input parameters are "exactly" known (e.g., joint orientations, shear strength, etc.). UnWedge computes the factors of safety for each wedge for a single wedge arrangement.

The following general procedure outlines the typical sequence of steps used to carry out a Deterministic Analysis with UnWedge:

  1. Project Settings: Make sure you select a Deterministic Analysis type in the General tab. Select the desired Unit System (metric or imperial) and if you are analyzing End Wedges, make sure the Compute End Wedges checkbox is selected. You may use a Design Standard from the Design Standard tab, and you may also specify a Project Title from the Project Summary tab.
  2. Define Opening Section (Add Opening Section / Import DXF): Define the opening cross-section of your excavation with the Add Opening Section option or import the coordinates from a DXF file. You can also define or import a Ground Surface or a Truncation Surface at this step.
  3. Input Data > Tunnel Axis Orientation, Unit Weight: Enter the Tunnel Axis Orientation and the rock unit weight under the General tab of the Input Data dialog.
  4. Input Data > Joint Orientations: Enter the joint orientations under the Joint Orientations tab of the Input Data dialog. Joint orientations can also be imported from a Dips file.
  5. Input Data > Joint Properties: Enter the joint properties (strength, water pressure, structure) under the Joint Properties tab of the Input Data dialog.
  6. Assign Joint Properties: If your joints have different properties, assign the desired properties to the joints under the Joint Orientations tab of the Input Data dialog.
  7. 3D Wedge View: View the results in the 3D Wedge View, which provides Perspective, Top, Front and Side views of the excavation and all of the possible wedges that are formed. Results can also be viewed in the Multi-Perspective View or the End Wedge View.
  8. Wedge Information: Detailed analysis results (Factor of Safety, wedge weights, etc.) are available in the Wedge Information Panel of the Sidebar. Also, the Info Viewer provides a comprehensive summary of model input data and analysis results.
  9. Scale Wedges: By default, UnWedge initially calculates the maximum-sized wedges that can form around the excavation. Use the Scale Wedges options to scale down the size of the wedges according to actual field observations (e.g., observed joint trace lengths).
  10. Support Design (Bolts / Shotcrete / Pressure): If any wedges require support to achieve the design Factor of Safety, you can add bolts, shotcrete, or pressure support to the model to determine the support requirements that are necessary. Use the Perimeter Support Design View to define support around the perimeter of the excavation. Use the End Support Design View to define support for the End Wedges of the excavation.
  11. Iterate Support Design: Experiment with the support parameters (e.g., bolt spacing, length, properties), until you have achieved a satisfactory support design for the model.
  12. Advanced Features:
  • Combination Analyzer: If you have more than three joint planes of interest, the Combination Analyzer option will automatically analyze all possible combinations of three joint planes. A summary of results allows you to determine which joint combinations are the most critical.
  • Field Stress: With the Field Stress option, you may include the effect of in-situ stress (clamping stress) on the Factor of Safety of the wedges.
  • Tunnel Orientation Analyzer: The Tunnel Orientation Analyzer option analyzes a range of tunnel axis trends and plunges, for any or all joint combinations. It allows you to identify the critical minimum or maximum values and the tunnel orientation(s) and joint combination(s) that produce them.
  • Tunnel Axis Plot: A Tunnel Axis Plot (contour, 3D or 2D chart) allows you to optimize the tunnel orientation with respect to any variable (e.g., required support pressure) within any user-defined range of tunnel orientation (trend, plunge).
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