Index: DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauCurveTests.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauCurveTests.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauCurveTests.cs	(revision 4556)
@@ -0,0 +1,112 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System.Collections.Generic;
+using Deltares.DamEngine.Data.Geotechnics;
+using NUnit.Framework;
+
+namespace Deltares.DamEngine.Data.Tests.Geotechnics;
+
+[TestFixture]
+public class SigmaTauCurveTests
+{
+    [Test]
+    public void GivenSigmaTauCurveWhenSettingNameThenNameIsSetCorrectly()
+    {
+        // Given
+        var curve = new SigmaTauCurve();
+        var expectedName = "Test Curve";
+
+        // When
+        curve.Name = expectedName;
+
+        // Then
+        Assert.AreEqual(expectedName, curve.Name);
+    }
+
+    [Test]
+    public void GivenSigmaTauCurveWhenInitializingPointsThenPointsAreInitializedCorrectly()
+    {
+        // Given
+        var curve = new SigmaTauCurve();
+
+        // When
+        List<SigmaTauPoint> points = curve.Points;
+
+        // Then
+        Assert.IsNotNull(points);
+        Assert.IsInstanceOf<List<SigmaTauPoint>>(points);
+        Assert.AreEqual(0, points.Count);
+    }
+
+    [Test]
+    public void GivenSigmaTauCurveWhenAddingPointThenPointIsAddedCorrectly()
+    {
+        // Given
+        var curve = new SigmaTauCurve();
+        var point = new SigmaTauPoint
+        {
+            Sigma = 1.0,
+            Tau = 2.0
+        };
+
+        // When
+        curve.Points.Add(point);
+
+        // Then
+        Assert.AreEqual(1, curve.Points.Count);
+        Assert.AreEqual(point, curve.Points[0]);
+    }
+
+    [Test]
+    public void GivenTwoSigmaTauCurvesWhenAssigningThenPropertiesAreAssignedCorrectly()
+    {
+        // Given
+        var sourceCurve = new SigmaTauCurve
+        {
+            Name = "Source Curve"
+        };
+        sourceCurve.Points.Add(new SigmaTauPoint
+        {
+            Sigma = 1.0,
+            Tau = 2.0
+        });
+        sourceCurve.Points.Add(new SigmaTauPoint
+        {
+            Sigma = 3.0,
+            Tau = 4.0
+        });
+
+        var targetCurve = new SigmaTauCurve();
+
+        // When
+        targetCurve.Assign(sourceCurve);
+
+        // Then
+        Assert.AreEqual(sourceCurve.Name, targetCurve.Name);
+        Assert.AreEqual(sourceCurve.Points.Count, targetCurve.Points.Count);
+        for (var i = 0; i < sourceCurve.Points.Count; i++)
+        {
+            Assert.AreEqual(sourceCurve.Points[i].Sigma, targetCurve.Points[i].Sigma);
+            Assert.AreEqual(sourceCurve.Points[i].Tau, targetCurve.Points[i].Tau);
+        }
+    }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/Soil.cs
===================================================================
diff -u -r4540 -r4556
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/Soil.cs	(.../Soil.cs)	(revision 4540)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/Soil.cs	(.../Soil.cs)	(revision 4556)
@@ -89,6 +89,11 @@
         CuBottom = aSoil.CuBottom;
         UsePop = aSoil.UsePop;
         StrengthIncreaseExponent = aSoil.StrengthIncreaseExponent;
+        if ((ShearStrengthModel == Geotechnics.ShearStrengthModel.SigmaTauCurve) && (aSoil.SigmaTauCurve != null))
+        {
+            SigmaTauCurve = new SigmaTauCurve();
+            SigmaTauCurve.Assign(aSoil.SigmaTauCurve);
+        }
     }
 
     #region property Name
@@ -261,5 +266,10 @@
     /// </value>
     public double SlopeRestProfile { get; set; } = double.NaN;
 
+    /// <summary>
+    /// The sigma tau curve (for Shear Strength Model = SigmaTauCurve)  
+    /// </summary>
+    public SigmaTauCurve SigmaTauCurve { get; set; }
+
     #endregion
 }
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauCurve.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauCurve.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauCurve.cs	(revision 4556)
@@ -0,0 +1,51 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System.Collections.Generic;
+
+namespace Deltares.DamEngine.Data.Geotechnics;
+
+/// <summary>
+/// The Sigma Tau curve.
+/// </summary>
+public class SigmaTauCurve
+{
+    /// <summary>
+    /// The name.
+    /// </summary>
+    public string Name { get; set; }
+
+    /// <summary>
+    /// The points of the curve.
+    /// </summary>
+    public List<SigmaTauPoint> Points { get; } = new();
+
+    /// <summary>
+    /// Assigns the specified curve.
+    /// </summary>
+    /// <param name="curve"></param>
+    public void Assign(SigmaTauCurve curve)
+    {
+        Name = curve.Name;
+        Points.Clear();
+        Points.AddRange(curve.Points);
+    }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauPoint.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauPoint.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SigmaTauPoint.cs	(revision 4556)
@@ -0,0 +1,48 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+namespace Deltares.DamEngine.Data.Geotechnics;
+
+/// <summary>
+/// The Sigma Tau point.
+/// </summary>
+public class SigmaTauPoint
+{
+    /// <summary>
+    /// The sigma.
+    /// </summary>
+    public double Sigma { get; set; }
+
+    /// <summary>
+    /// The tau.
+    /// </summary>
+    public double Tau { get; set; }
+
+    /// <summary>
+    /// Assigns the specified point.
+    /// </summary>
+    /// <param name="point"></param>
+    public void Assign(SigmaTauPoint point)
+    {
+        Sigma = point.Sigma;
+        Tau = point.Tau;
+    }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/ShearStrengthModel.cs
===================================================================
diff -u -r4551 -r4556
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/ShearStrengthModel.cs	(.../ShearStrengthModel.cs)	(revision 4551)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/ShearStrengthModel.cs	(.../ShearStrengthModel.cs)	(revision 4556)
@@ -34,5 +34,10 @@
     /// <summary>
     /// The Su calculated model (with POP)
     /// </summary>
-    SuCalculated = 2
+    SuCalculated = 2,
+    
+    /// <summary>
+    /// The Sigma Tau curve model
+    /// </summary>
+    SigmaTauCurve = 3
 }
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauPointTests.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauPointTests.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SigmaTauPointTests.cs	(revision 4556)
@@ -0,0 +1,76 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using Deltares.DamEngine.Data.Geotechnics;
+using NUnit.Framework;
+
+namespace Deltares.DamEngine.Data.Tests.Geotechnics;
+
+[TestFixture]
+public class SigmaTauPointTests
+{
+    [Test]
+    public void GivenSigmaTauPointWhenSettingSigmaThenSigmaIsSetCorrectly()
+    {
+        // Given
+        var point = new SigmaTauPoint();
+        var expectedSigma = 1.0;
+
+        // When
+        point.Sigma = expectedSigma;
+
+        // Then
+        Assert.AreEqual(expectedSigma, point.Sigma);
+    }
+
+    [Test]
+    public void GivenSigmaTauPointWhenSettingTauThenTauIsSetCorrectly()
+    {
+        // Given
+        var point = new SigmaTauPoint();
+        var expectedTau = 2.0;
+
+        // When
+        point.Tau = expectedTau;
+
+        // Then
+        Assert.AreEqual(expectedTau, point.Tau);
+    }
+
+    [Test]
+    public void GivenTwoSigmaTauPointsWhenAssigningThenPropertiesAreAssignedCorrectly()
+    {
+        // Given
+        var sourcePoint = new SigmaTauPoint
+        {
+            Sigma = 1.0,
+            Tau = 2.0
+        };
+        var targetPoint = new SigmaTauPoint();
+
+        // When
+        targetPoint.Assign(sourcePoint);
+
+        // Then
+        Assert.AreEqual(sourcePoint.Sigma, targetPoint.Sigma);
+        Assert.AreEqual(sourcePoint.Tau, targetPoint.Tau);
+    }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SoilTests.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SoilTests.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/SoilTests.cs	(revision 4556)
@@ -0,0 +1,97 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using Deltares.DamEngine.Data.Geotechnics;
+using NUnit.Framework;
+
+namespace Deltares.DamEngine.Data.Tests.Geotechnics;
+
+[TestFixture]
+public class SoilTests
+{
+        [Test]
+        public void GivenTwoSoilsWhenAssigningThenPropertiesAreAssignedCorrectly()
+        {
+            // Given
+            var sourceSoil = new Soil("Source Soil", 10.0, 20.0)
+            {
+                BeddingAngle = 30.0,
+                DiameterD70 = 0.5,
+                PermeabKx = 0.01,
+                WhitesConstant = 1.2,
+                DiameterD90 = 0.7,
+                Cohesion = 5.0,
+                FrictionAngle = 25.0,
+                PoP = 100.0,
+                Ocr = 1.5,
+                RatioCuPc = 0.8,
+                CuTop = 2.0,
+                CuBottom = 3.0,
+                UsePop = true,
+                StrengthIncreaseExponent = 0.3,
+                ShearStrengthModel = ShearStrengthModel.SigmaTauCurve,
+                SigmaTauCurve = new SigmaTauCurve
+                {
+                    Name = "Curve"
+                }
+            };
+            sourceSoil.SigmaTauCurve.Points.Add(new SigmaTauPoint
+            {
+                Sigma = 1.0,
+                Tau = 2.0
+            });
+            sourceSoil.SigmaTauCurve.Points.Add(new SigmaTauPoint
+            {
+                Sigma = 3.0,
+                Tau = 4.0
+            });
+            
+            var targetSoil = new Soil();
+
+            // When
+            targetSoil.Assign(sourceSoil);
+
+            // Then
+            Assert.AreEqual(sourceSoil.Name, targetSoil.Name);
+            Assert.AreEqual(sourceSoil.BeddingAngle, targetSoil.BeddingAngle);
+            Assert.AreEqual(sourceSoil.DiameterD70, targetSoil.DiameterD70);
+            Assert.AreEqual(sourceSoil.PermeabKx, targetSoil.PermeabKx);
+            Assert.AreEqual(sourceSoil.WhitesConstant, targetSoil.WhitesConstant);
+            Assert.AreEqual(sourceSoil.DiameterD90, targetSoil.DiameterD90);
+            Assert.AreEqual(sourceSoil.Cohesion, targetSoil.Cohesion);
+            Assert.AreEqual(sourceSoil.FrictionAngle, targetSoil.FrictionAngle);
+            Assert.AreEqual(sourceSoil.PoP, targetSoil.PoP);
+            Assert.AreEqual(sourceSoil.Ocr, targetSoil.Ocr);
+            Assert.AreEqual(sourceSoil.RatioCuPc, targetSoil.RatioCuPc);
+            Assert.AreEqual(sourceSoil.CuTop, targetSoil.CuTop);
+            Assert.AreEqual(sourceSoil.CuBottom, targetSoil.CuBottom);
+            Assert.AreEqual(sourceSoil.UsePop, targetSoil.UsePop);
+            Assert.AreEqual(sourceSoil.StrengthIncreaseExponent, targetSoil.StrengthIncreaseExponent);
+            Assert.AreEqual(sourceSoil.ShearStrengthModel, targetSoil.ShearStrengthModel);
+            Assert.AreEqual(sourceSoil.SigmaTauCurve.Name, targetSoil.SigmaTauCurve.Name);
+            Assert.AreEqual(sourceSoil.SigmaTauCurve.Points.Count, targetSoil.SigmaTauCurve.Points.Count);
+            for (int i = 0; i < sourceSoil.SigmaTauCurve.Points.Count; i++)
+            {
+                Assert.AreEqual(sourceSoil.SigmaTauCurve.Points[i].Sigma, targetSoil.SigmaTauCurve.Points[i].Sigma);
+                Assert.AreEqual(sourceSoil.SigmaTauCurve.Points[i].Tau, targetSoil.SigmaTauCurve.Points[i].Tau);
+            }
+        }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/Deltares.DamEngine.Calculators.csproj
===================================================================
diff -u -r4540 -r4556
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/Deltares.DamEngine.Calculators.csproj	(.../Deltares.DamEngine.Calculators.csproj)	(revision 4540)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/Deltares.DamEngine.Calculators.csproj	(.../Deltares.DamEngine.Calculators.csproj)	(revision 4556)
@@ -29,7 +29,7 @@
     </ItemGroup>
     <ItemGroup>
         <PackageReference Include="Deltares.Geo.Common.Standard">
-            <Version>23.2.1.39</Version>
+            <Version>24.1.1.43</Version>
         </PackageReference>
         <PackageReference Include="Deltares.StixFileWriter">
             <Version>23.2.1.6</Version>