Optimizing an Anchored Excavation Design with DeepEX
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- 4 min read
DeepEx Software Automatic Optimization Options
Designing anchored excavation systems is an inherently iterative process. Engineers must satisfy both structural and geotechnical requirements while maintaining an efficient and constructible solution. In many cases, the initial design meets some criteria but fails others, requiring multiple adjustments before reaching an optimal configuration.
DeepEX streamlines this process by combining rapid model generation, robust analysis methods, and targeted optimization tools. Instead of relying on trial-and-error, engineers can quickly identify inefficiencies and refine their design in a controlled and rational way.
This article presents how DeepEX can be used to optimize an anchored sheet pile wall supporting a 40 ft excavation.
Rapid Model Generation
The entire excavation model can be generated instantly using a simple command:
“Create a 40 feet excavation with 3 levels of tiebacks”
With this input, DeepEX automatically defines the wall, support system, and construction stages. This allows the engineer to immediately proceed to defining soil conditions and evaluating system performance, rather than spending time on manual setup.
Figure 1: Type commands, generated model and construction stages – DeepEX
Project Definition
The excavation is supported by a steel sheet pile wall (AZ19, A50 steel) with a total depth of 62 ft. Three levels of tiebacks are installed along the wall, each initially designed with four strands.
Support System
Level | Elevation (ft) | Strands | Lfree (ft) | Lfix (ft) | Spacing (ft) |
1 | -8 | 4 | 27.5 | 25 | 8 |
2 | -18 | 4 | 22.9 | 25 | 8 |
3 | -28 | 4 | 17.4 | 25 | 8 |
The subsurface profile consists of three distinct layers, each contributing differently to both earth pressures and anchor capacity.
Soil Stratigraphy
Layer | Elevation (ft) | Soil Type | γ (pcf) | φ (°) | c′ (psf) | Qskin (psi) |
F | 0 to -10 | Fill Sand | 120 | 30 | 0 | 10 |
S1 | -10 to -25 | Medium Dense Sand | 130 | 34 | 10 | 25 |
GT | -25+ | Glacial Till | 135 | 36 | 150 | 35 |
These soil properties directly influence both the earth pressure distribution and the pullout resistance of the anchors, making stratigraphy a key factor in the optimization process.
Figure 2: Stratigraphy in DeepEX software
Analysis Methodology
The system is analyzed using the Limit Equilibrium Method, following the CALTRANS beam analysis approach. Negative moments are reduced by 20%, wall friction is neglected, and earth pressures are defined using active and passive conditions for the cantilever stage, transitioning to FHWA apparent pressures once supports are installed.
DeepEX computes soil, water, and surcharge pressures separately and combines them into a net pressure diagram. This diagram forms the basis for calculating wall moments, shear forces, anchor reactions, and embedment safety factors.
While this approach provides a reliable initial design, it is the evaluation of anchor performance that drives optimization.
Initial Design Evaluation
The first analysis highlights how different anchors respond to loading and soil conditions.
Level | Structural Ratio (STR) | Geotechnical Ratio (GEO) | Status |
1 | 0.756 | 1.187 | GEO overstressed |
2 | 0.709 | 0.864 | OK |
3 | 1.341 | 1.633 | STR & GEO overstressed |
The upper anchor is structurally adequate but lacks sufficient pullout resistance. The middle anchor performs well and requires no modification. The lowest anchor, however, is overstressed in both structural and geotechnical terms, indicating that both its steel capacity and its embedment length are insufficient.
This outcome reflects typical real-world behavior, where deeper anchors are subjected to higher loads and require stronger soil engagement.
Figure 3: Initial model results in DeepEX: Wall moments, support reactions, structural & geotechnical check ratios for each support level
Optimization Process
DeepEX allows direct optimization of both structural capacity and geotechnical performance without manual iteration.
For structural adequacy, the software can automatically propose an improved anchor section. In this case, the lowest anchor is upgraded from four to six strands, reducing the structural ratio to an acceptable level while maintaining efficiency.
Geotechnical performance is addressed by optimizing the fixed length of each anchor. The software evaluates the required embedment based on soil-specific bond strength and safety factors.
The resulting adjustments are:
Level 1: Fixed length increased from 25 ft to 30 ft
Level 3: Fixed length increased from 25 ft to 45 ft
These changes ensure that sufficient bond resistance is mobilized within the surrounding soils, particularly in the stronger glacial till layer.
Final Optimized Design
After applying the necessary adjustments, all anchors satisfy both structural and geotechnical criteria.
Level | STR | GEO | Final Configuration |
1 | 0.756 | 0.934 | Increased Lfix |
2 | 0.709 | 0.864 | Unchanged |
3 | 0.895 | 0.907 | 6 strands + increased Lfix |
The final design achieves a balanced solution. Utilization ratios are below unity but remain close enough to avoid unnecessary conservatism. Material use is optimized, and the system performs efficiently under the defined loading conditions.
Figure 4: Structural sections optimization – DeepEX
Figure 5: Anchor fixed length optimization – DeepEX
Figure 6: DeepEX – optimized model with analysis results
Engineering Interpretation
This example illustrates that structural and geotechnical checks must be treated independently. An anchor that is structurally sufficient may still fail in pullout if the surrounding soil cannot provide adequate resistance.
It also highlights the importance of soil stratigraphy. The need to extend anchor lengths into deeper layers is driven by the requirement to mobilize stronger soils with higher bond capacity.
Most importantly, the example demonstrates how DeepEX transforms the design workflow. Instead of repeatedly adjusting parameters and re-running analyses, engineers can apply targeted optimizations and immediately evaluate their impact.
Conclusion
Optimizing anchored excavation systems requires a clear understanding of both structural demand and soil behavior. DeepEX provides the tools to achieve this efficiently, combining automated model generation, rigorous analysis, and intelligent optimization within a single platform.
The result is a design process that is not only faster, but also more transparent and technically robust—allowing engineers to focus on decision-making rather than iteration.
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