From Model Preparation to Analysis of Results
Nonlinear finite element analysis of ground and structures, with single- and two-phase formulations for plane-strain, axisymmetric and three-dimensional models.
Partial saturation is represented using Bishop’s effective stress principle, with the suction–saturation relationship described by the van Genuchten soil–water retention model.
Analysis Capabilities
Choose analysis methods to represent the processes and construction sequence relevant to your project.
Initial State
Evaluate initial stresses, including steady-state flow and existing constructions, by combining gravity and initial-stress conditions.
Ultimate Load & Deformation
Apply stress- or strain-imposed simulations to excavation, foundation, construction, tunnelling and other boundary-value problems.
Stability
Use tan(ϕ)–c reduction and stress-level algorithms to assess safety factors and failure surfaces. Assess safety with respect to local material properties and contact surfaces.
Construction Stages
Add or remove construction parts, loads and boundary conditions. Combine excavation and filling stages with analysis drivers, unloading control for 3D effects in 2D, and continuous safety assessment.
Time-Dependent Behaviour
Model consolidation, volumetric and deviatoric creep, and swelling.
Groundwater Flow
Analyse steady or transient flow in fully or partially saturated media, coupled or uncoupled with solid deformation. Include time-dependent boundaries, free surfaces, seepage surfaces, rainfall inflow and impermeable zones.
Thermal & Moisture Migration
Perform transient thermal or moisture-migration analyses as preprocessing, with temperature time histories subsequently used in mechanical analysis.
Dynamics & Pushover
Use dynamic time integration and structural pushover analysis, including soil–structure interaction.
Probabilistic Analysis & Reliability
Represent uncertainty in model inputs, assess reliability and calibrate parameters against measurements.
Random Variables & Sampling
Define uncertain material parameters, loads and construction timings. Generate samples using Monte Carlo, Latin Hypercube, Sobol or Halton methods.
Metamodelling & Accuracy Assessment
Approximate model responses with Kriging, PCE or PCK, and check prediction accuracy through cross-validation.
Sensitivity Analysis
Identify influential parameters using Sobol indices, linear correlation or standard regression coefficients.
Reliability Analysis
Estimate failure probabilities for defined limit states using Monte Carlo analysis of the metamodel. Review convergence and confidence intervals.
Active Learning Reliability
Automatically refine the metamodel with additional ZSoil simulations to improve failure-probability estimates.
Bayesian Calibration & Back Analysis
Update parameter distributions using measurements, accounting for measurement and modelling uncertainty. Assess predictions and reliability after calibration.
Uses UQLab and requires MATLAB Runtime R2023b.
Structural Elements & Loading
Represent structural components, their interaction with the ground and their loading conditions.
- Trusses
- Elastic or elastoplastic behaviour.
- Anchors
- Elastic or elastoplastic anchorage sections.
- Beams
- Elastic or composite beams, including core material and reinforcement. Displacement-based and flexibility-based formulations use two and five Gauss points, respectively. The former is compatible with interfaces and suited to underground structures; the latter is suited to above-ground structures, with one finite element per structural member.
- Nails
- Embedded beams with ultimate shear-strength resistance.
- Piles & Barrettes
- Embedded beams with Coulomb-friction interfaces, using local or nonlocal formulations. The nonlocal formulation reduces mesh dependency and supports circular and quadrilateral cross-sections for piles and barrettes, with good convergence behaviour for fine meshes.Piles and barrettes report (PDF)
- Tendons
- Pretensioned or posttensioned cables.
- Membranes
- Elastic or elastoplastic behaviour.
- Thin & Thick Shells
- Elastic or nonlinear composite behaviour.
- Moving Loads & Masses
- Apply loads and masses along defined paths, including curved paths in 3D, with constant or variable velocity.Moving loads presentation (PDF)
Loading conditions: include prestress for anchors, struts and tendons, as well as imposed stresses or strains, for example thermal dilation of struts.
Constitutive Models
Continuum models for soils, rocks and structural materials.
- Elastic
- Reversible stress–strain response for materials represented by elastic behaviour.
- Elastic for Structures
- Elastic continuum representation of structural components.
- Mohr–Coulomb
- Elastoplastic model with frictional strength and cohesion for basic soil and rock analyses.
- Hardening Soil
- Stress-dependent stiffness and plastic hardening, with HS-small and HS-Brick formulations for small-strain behaviour. Cross-anisotropic stiffness options are available.Hardening Soil report (PDF)
- Hoek–Brown
- Nonlinear rock-strength model, with original and advanced formulations including hardening and softening.Hoek–Brown report (PDF)
- Multi-laminate
- Representation of directional behaviour in foliated rocks through material planes.Multilaminate report (PDF)
- Drucker–Prager
- Pressure-dependent plasticity using a smooth yield surface for frictional materials.
- Modified Cam-Clay
- Critical-state model for clay behaviour, accounting for preconsolidation and plastic volumetric deformation.
- Cap Model
- Elastoplastic model with volumetric hardening for pressure-dependent yielding and irreversible compression.
- Densification
- Representation of soil densification and liquefaction-related behaviour under cyclic loading.
- Menétrey–Willam
- Concrete strength and plasticity model for a simplified representation of nonlinear concrete behaviour.
- Damage-Plastic Concrete
- Combined damage and plasticity for advanced concrete modelling, including a fire extension.Concrete damage report (PDF) · Fire report (PDF)
Virtual Lab supports parameter selection for soil models through expert-knowledge-based estimation and parameter identification from laboratory tests.Virtual Lab report (PDF)
ZSoil 2026 introduces stiffness cross-anisotropy for HS-small and HS-Brick using the xA2 concept, with tools for setting parameters and mapping between isotropic and anisotropic stiffness descriptions.
Modelling Workflow
Prepare geometry and model data, then inspect, export and process the computed results.
Data Preparation
- Import CAD geometry from DXF and Rhino formats.
- Work flexibly during model preparation.
- Check model data using consistency-verification tools.
- Manage materials, load functions and boreholes through interfaces updated in ZSoil 2026.
- Edit multiple load entries using the load table’s bulk-edit facility.
- Build geological models from boreholes and kriging interpolation.
- Reuse materials, boreholes, geometry and other data from existing models.
- Assemble a final model from subsidiary models to support teamwork.
Analysis of Results
- Inspect computed variables using colour maps, diagrams and time histories.
- Generate envelope diagrams.
- Export data to CSV.
- Customise data analysis and reporting with the Python SDK.
- Export results to ParaView for alternative viewing.
Numerical Formulation & Solvers
Finite element formulations and solution methods.
ZSoil uses linear elements enhanced with BBAR, enhanced strains and stabilised formulations to address locking phenomena. Element types include trusses, cables, beams, membranes, thin and thick shells, and continuum elements for single- and two-phase media.
Skyline and sparse solvers are available.
Parallel Computation
ZSoil 2026 supports shared-memory parallel computation, with the number of threads set under Control → Parallel computation. Performance gains depend on model size, the nonlinear solver and the number of iterations.
Published ZSoil 2026 examples report speedups from 1.4 to more than 5 times. These are benchmark results rather than a guaranteed speedup for every model.
Hydro-Thermal Processes & Heat Exchangers
Represent water retention, heat transport and heat-exchanger systems in the ground.
Soil–Water Retention
The full Van Genuchten soil–water retention curve is available, together with a calculator for estimating its parameters from standard geotechnical data.
Weakly Coupled Hydro-Thermal Analysis
Solve seepage first, then perform thermal analysis using fluid velocities mapped from the seepage mesh to the thermal mesh. The formulation accounts for partial saturation, advection, effective thermal conductivity and volumetric heat capacity of the two-phase medium.
Explicit Heat Exchangers
Represent the heat pipe and refrigerant explicitly. Where grout is present, model it separately using standard continuum elements.
Implicit Heat Exchangers
Use a formulation in which the heat pipe and refrigerant are embedded in grout.
Specialised Tools & Learning Resources
Documentation, tutorials and examples to support your work with ZSoil.
ZSwalls
A diaphragm- and sheet-pile-wall template for PC use, also available as standalone software.
Python SDK & Automation
Use the Python SDK to customise the analysis of computed results and reporting, and integrate these tasks into your Python workflows.
ZSslope
A template for slope-stability modelling with steady-state or transient two-phase formulations, including rainfall inflow.
Hotline support and online Help are available to users. The Getting Started manual introduces basic workflows, while publications and case studies show engineering applications.
Numerics in Geotechnics and Structures 2015PDF
ZSoil in today’s projects — P. Jemec et al., ELEA iCPDF
Case studies with ZSoilWEB
ZSoil tutorialsWEB
The ELEA iC presentation includes comparisons between PHASE2, PLAXIS 3D, SOFiSTiK and ZSoil.