Slope Stability Analysis &
Design of Soil Nail Walls

Calculation of the Slope Stability Safety Factor with several methods

Multiple Failure Surface Search options and methods

Full Structural Design of all items: Soil Nails, Shotcrete Facing, Head Plates


Slope Stability FS and Check Ratios in SnailPlus


Stepped Soil Nail Wall Design with SnailPlus


Two-Stage Facing (Temporary and Permanent)

SnailPlus 2021 - Soil nail analysis software

SnailPlus is our slope stability analysis and soil nail wall design software. While soil nailing is also available in our DeepEX software program, SnailPlus was created to bring all the necessary capabilities into one package. The software follows the FHWA methodology for the design of soil nail walls, in an interactive environment built on the DeepEX basic layout. This means that you can include all intermediate construction stages for your soil nail wall, include 3D loads, all in an interactive environment. Last, SnailPlus is the only software that produces a full printable report of all design calculations.

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How the Software Works?

Why Choose SnailPlus?

The software has a superior interactive interface that allows you to create and edit any soil nail wall model in seconds. All items (shotcrete facing, soil nails, borings, loads etc) can be graphically added on the model area. We can include extrnal surcharges fast on the soil surface or on the facing directly, include seismic loads, examine extreme events, use custom soil surfaces (non horizontal stratigraphy) and more. In SnailPlus we can select to use a permanent or a two-stage facing (temporary in all stages - permanent in the last stage). The facing status can change on the model area with a click in any stage. The software allows us to examie all construction stages, and we can locate the most critical slope surface, the slope stability saftty factor and the soil nail - head plates - shotcrete facing results in each stage. Last but not least, SnailPlus is the only software that produces a full printable report of all design calculations.

Main Software Characteristics



SnailPlus global stability of slope surfaces (simple or reinforced with soil nails).

SnailPlus can calculate and report the most critical slope surface and the slope stability safety factor with the use of several scientific methods.

Soil nails can be used in the slope surfaces. SnailPlus calculates the effects of the soil nails to the slope stability analysis.

  • Bishop Method
  • Morgenstern-Price Method (General Limit Equilibrium)
  • Spencer Method
  • French Clouterre standards for the soil nail design



SnailPlus can locate and report the most critical slope surface using various slope surface search methods:

  • Circular Slope Surfaces
  • Circular Surfaces with Active and/or Passive Wedges
  • Automatic Surface Search Method
  • Trilinear Surface Search Methods
  • Surfaces with Block-type failure
  • User-Defined Slope Surfaces

Which slope stability method is best for your case?

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SnailPlus can design the shotcrete facing. Two stage facings (temporary and permanent) can be also defined and analyzed with the software.

SnailPlus performs checks on the soil nail head plates

  • Design of the shocrete facing
  • Two step facing available
  • Head plate checks



SnailPlus Model Wizard can be used to create any sloped surface with all construction stages, excavations and soil nail and facing installation in minutes. We can use the Wizard tabs to define all project parameters (sloped surface parameters, soil nail - head plates and shotcrete structural sections, stage options and design standards). The Wizard creates the model automatically, saving us a lot of time and effort for the initial creation



The soil types, soil properties and stratigraphies can be easily defined in SnailPlus through user-friendly dialogs.

In SnailPlus we can create an unlimited list of soils and define all soil properties quickly. The software provides several estimation tools (SPT Estimator and partial estimation tools for each property using scientific methods and equations).

In SnailPlus we can add directly SPT Records and CPT Logs, which can be used from the software to estimate various soil properties.

  • Define list of soil types
  • Define list of stratigraphies (borings)
  • Soil properties estimation tools
  • SPT Records 
  • CPT Logs

Full strustural and geotechnical design of your soil nail walls!

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SnailPlus is an extremely user-friendly software, which offers an interactive model interface. In the model area we can create all the stages stages and define all project parameters (external loads, soil nail sections, shotcrete section etc.) graphically.

All items on the model area (boring, soil nails, facing) can be accessed and their properties can be defined through user-friendly dialogs.



SnailPlus has implemented various different standards and specifications for the soil nails and shotcrete facing design.

In SnailPlus we can select ACI and FHWA specifications for the structural design. In the software we can either use Service Limit State or Ultimate Limit State methods.


  • ACI Direct method
  • FHWA and FHWA LRFD methods
  • LRFD WSDOT 2019 (GDM)
  • ASD Safety factors
  • EUROCODE 7 - ULS Approach



SnailPlus reports can include tables and graphs with all examined model properties and calculated results. We can also choose to include to the report all structural design equations and calculation procedure.

The SnaiPlus reports can be previewed, exported to PDF or exported to Word format, so they can be further edited by the user.

  • Select Design Sections to Report
  • Select Construction Stages to Report
  • Customize Report Graphs
  • Define Report Layout
  • Define Report Sections
  • Possibility to Report Equations and Stage Calculations
  • Preview the Report
  • Export Reports in PDF and Word Formats

SnailPlus - All software capabilities

Interactive environment Automatic failure search methods Full list of calculations and equations
Include all stages Circular failure search FHWA design standards
Model wizard Circular+Active and Passive wedge analysis LRFD WSDOT 2019 (GDM)
Include all design sections of the excavation into one file Block type analysis Two stage facing available
Groundwater and flownet modeling User defined failure surface analysis Shotcrete facing analysis
3D loads and other surcharge effects Trilinear surface search methods
  Head plate checks
AASHTO and EC7 Load Combinations Morgenstern Price, Spencer, Bishop analysis methods. Export reports to PDF and Word.

Training Video: Design of a Stepped Soil Nail Wall with SnailPlus Software

Video Example - Stepped Soil Nail Wall Design


Open Example Video



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