Which analysis method should I use?
- May 19
- 3 min read
Selecting the appropriate analysis method in DeepEX depends on the specific goals of your project and the level of detail and accuracy required in your analysis. Here's a breakdown of the key considerations for each method:
1. Conventional Limit Equilibrium Analysis Method (LEM):
When to Use:
This method is typically a starting point for analysis. It calculates support reactions for limit state conditions and wall embedment safety factors. In our opinion, you should always start with this method, even if you are performing a more advanced design.
Advantages:
Provides quick insights, especially for preliminary analysis and optimization. Useful for obtaining initial estimates and identifying potential critical conditions.
Considerations:
May produce less realistic results for wall displacements and shear forces, especially in complex, multilevel excavation projects.
Fig.: Anchored excavation – LEM analysis results in DeepEX
2. Non-linear Analysis Method with Elastoplastic Winkler Springs (NL):
When to Use:
Recommended for projects where a higher level of realism is desired, particularly in multi-level excavation scenarios.
Advantages:
Incorporates construction staging, providing more realistic results for wall displacements and shear forces. Suited for projects with complex sequences or stages.
Considerations:
May be computationally more intensive compared to LEM, and the accuracy is contingent on the realistic definition of material and soil properties. The method does not consider full soil-structure interaction and basal soil movements below the wall.
Fig.: Anchored excavation – Non-Linear analysis results in DeepEX
3. Finite Element Analysis Method (2D and 3D FEM):
When to Use:
Ideal for projects where one must consider full soil-structure interaction. Such cases can include studying the impact of an excavation on an existing tunnel or structure.
Advantages:
Produces more realistic results when appropriate material and soil properties are defined. Enables detailed modeling of complex geometries and construction sequences.
Considerations:
Requires thorough understanding of soil-structure interaction and elastic soil models. Accuracy is highly dependent on the quality of input parameters and the complexity of the model. Models can take longer to compute, especially for 3D analyses. For models to converge users need to accept some level of convergence error, typically in the 3% range. Reviewers need to be careful as small parameter changes may lead to significantly different results, especially for undrained clays.
Fig.: Anchored excavation – Finite Element analysis results in DeepEX
Practical Recommendations:
In practice, a combination of these methods, considering the most critical results from each, can provide a comprehensive understanding of the excavation behavior and contribute to effective decision-making during the design and optimization process.
For projects without any adjacent buildings and reasonable soil conditions where the excavation requires a maximum of two levels of bracing, the conventional and the non-linear analysis methods should be sufficient. When excavating next to adjacent structures or tunnels, or soil conditions are challenging, or for deeper excavations, we should also consider the finite element method.
Preliminary Analysis: Start with the Conventional Limit Equilibrium Analysis for quick insights and initial model optimization.
Intermediate Complexity: Consider Non-linear Analysis for a more detailed and realistic representation of wall displacements and shear forces, especially in multi-level excavation projects.
Complex Modeling: Run Finite Element Analysis when the project requires soil-structure interaction.
Even after running all analysis types, there is no replacement for sound engineering judgement. Always review results and make sure that they meet expected performance.
Let us show you how to reduce your design time by up to 90%!
