Plaxis 2D V20: Lesson 2 Submerged Construction of an Excavation

Introduction

This tutorial provides a step-by-step guide on performing submerged construction of an excavation using Plaxis 2D V20. This software is essential for analyzing deformation, stability, and fluid flow in geotechnical engineering. By following these steps, you will gain a comprehensive understanding of how to model submerged excavations effectively.

Step 1: Setting Up the Plaxis 2D Environment

• Open Plaxis 2D V20 on your computer.
• Familiarize yourself with the user interface. Key areas include:
  • Project manager
  • Input window
  • Output window
• Access the manuals for detailed guidance located at:

  C:\Program Files\Bentley\Geotechnical\PLAXIS 2D CONNECT Edition V20\manuals
  

• Create a new project by selecting "New Project" from the project manager.

Step 2: Defining Project Parameters

• Input the project name and select the appropriate units for your project.
• Define the geometry of the excavation:
  • Use the drawing tools to outline the excavation area.
  • Specify the depth and width of the excavation based on project requirements.
• Set the material properties:
  • Choose soil types (e.g., clay, sand) and input their physical and mechanical properties like density, cohesion, and friction angle.

Step 3: Modeling Submerged Conditions

• Define the water level in the model:
  • Go to the boundary conditions section and set the water table level.
  • Specify the hydrostatic pressure in the submerged area.
• Input any additional loading conditions, such as surcharge loads or adjacent structures.

Step 4: Mesh Generation

• Generate the finite element mesh:
  • Navigate to the mesh generation tool and create a mesh that captures the geometry of the excavation.
  • Ensure the mesh is fine enough to accurately represent stresses in critical areas.
• Review and adjust the mesh if necessary to avoid overly coarse elements.

Step 5: Setting Up Analysis Phases

• Define construction stages:
  • Create multiple phases to simulate the construction process step by step.
  • Include excavation, installation of support systems, and backfilling if applicable.
• Assign appropriate analysis types for each phase (e.g., consolidation, stability) based on the project requirements.

Step 6: Running the Analysis

• Select the analysis option from the main menu and choose the relevant phases to analyze.
• Monitor the progress of the calculation:
  • Check for any errors or warnings that may arise during the analysis.
• Upon completion, review the results for each phase.

Step 7: Interpreting Results

• Analyze the output results:
  • Look for displacement, stress distribution, and the factor of safety.
  • Use graphical tools to visualize results and identify potential issues.
• Generate reports summarizing the findings and recommendations for construction practices.

Conclusion

You have now learned how to perform submerged construction of an excavation using Plaxis 2D V20. Key steps include setting up the environment, defining parameters, modeling submerged conditions, and interpreting the results. For further learning, consider exploring additional lessons in the Plaxis 2D series or reviewing the manuals for advanced features.