gts 2d tutorial 18

MIDAS/ GTS 2D Tutorial 18 MIDAS IT Co., Ltd.

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MIDAS/GTS 2D Tutorial 18

Soil Nailing Reinforcement Slope

Stability Analysis



Starting Files Required

1. Introduction

Slope soil Nail reinforcement for weathered rock.

Extract and Divide 1D Nail elements.

Generating high order mesh for Strength Reduction method.

GTS 2D Tutorial 18.gtb

Soft Rock

Weathered Rock Layer

Weathered Soil

Nail



2. Material Properties

Mesh Set and Attribute

Attribute

Name(ID)Type Material Name(ID) Property Name(ID)

Mesh Set

Name

Weathered

Rock(1)Weathered Rock(1) -

Weathered

Rock

Weathered Soil(2) Plane Weathered Soil(2) - Weathered Soil

Soft Rock(3) Plane Soft Rock(3) - Soft Rock

Nail(4) Line Nail(4) Nail(1) Nail



3. Starting GTS

1 Open GTS 2D Tutorials 18.gtb 2 Display Option

Start GTS.exe

Click on File>Open

Open file GTS_2D_Tutorial 18.gtbFrom Main Menu, select View>Display Option.

Define False for Mesh > Node Display under General Tab.

Click OK



4. Input Material Properties

3 Attribute Generation

Model > Property > Attribute

After ensuring that all the generated Attributes, Materials, and Properties are listed, click Close.



5. Geometry modifications

4 Intersect

Geometry > Curve > Intersect

To register each mesh set independently, it is necessary to separate the geometry accordingly. This can be done by using the intersect function which separates all nodal connections.

From Main Menu, select Geometry > Curve > Intersect.

Click button or (Ctrl+A) to select the entire geometry.

Click [Apply] to perform the intersections.



6. Mesh Generation

5_1 Auto Mesh Planar Area

Mesh > Auto Mesh > Planar Area(F7)

1

1

2

From Main Menu, select Mesh>Auto Mesh>Planar Area or click [F7].

Select Object Edges shown in diagram 1.

Select Mesher Type as Quadrilateral.

Under Mesh Size, enter Element Size as 2.

Select Attribute ID 1: Weathered Rock and enter Mesh Set nameWeathered Rock .

Select the Generate Mid-Side Nodes option.

Click [Apply] button.

Repeat the same steps for the Weathered Soil for the layer selected in diagram 2. When defining mesh size, use Element size 3



6. Mesh Generation

5_2 Auto Mesh Planar Area

Mesh > Auto Mesh > Planar Area(F7)

High order mesh is required to perform a stability analysis on the slope using Strength Reduction Method. Generate Mid-Side Nodes generates a higher order Mesh set.



6 Extract Element

Model > Element > Extract Element

From Main Menu, select Model > Element > Extract Element.

From Shape select Edge.

As shown in the diagram, select the 14 edges.

Assign Attribute ID 4: Nail.

In Mesh Set, enter Nail.

Click [OK] button.



7 Divide 1D Element

Model > Element > Divide 1D Element

From Main Menu, select Model > Element > Divide 1D Element.

As shown in the diagram, select the Nail elements.

Enter 2 for Number of Division.

Select the Merge Nodes option.

Click [OK] button.

Nail elements were made by extracting 1D element; however, the mesh sets for nail and ground are not properly connected. The reason is because GTS does not support provides quadratic 1D element. Therefore, the Divide 1D element function must be used to match the connectivity between the nail and ground mesh set.



8 Element Coordinate System

From Main Menu, select Model > Element > Change Parameters.

First, select Align Local Csys.

As shown in the diagram select one Base Element.

The remaining elements will follow the same Csys with respect to the Base Elements Csys.

Click [OK] button.

From Pre-Works, select Mesh > Mesh Set and right click Mesh Set Nail.

As shown in the diagram, the elements Csys should be displayed.



9 Final Mesh Generation



7. Boundary Conditions

10 Supports

In the BC Set box, enter the name of the Support for x-direction. In this case, it is called Ground BC.

Click [Apply] button. Repeat the same steps for the ground support in the z and x -direction. Be sure to select the proper DOF

Model > Boundary > Supports

1

Caution should be exercised when selecting the nodes when defining Boundary conditions for mesh sets of higher order.



11 Self Weight

Model > Load > Self Weight

From Main Menu, select Model > Load > Self Weight.

In Load Set, enter Self-Weight

Enter Self Weight Factor for Z-direction as -1.

Click [OK] button.



8. Analysis Case

12 Setting up Analysis Case

From Main Menu, select Analysis > Analysis Case.

Click [Add] button and to perform Analysis Case.

In Name, enterSoil Nailing reinforcement slope stability analysis.

Select Slope Stability SRM as the Analysis Type.

As shown in the diagram, Drag and Drop all of the Elements, Boundary, and Load from Set tree to the Activated column.

Click [OK] button.

Analysis > Analysis Case



13 Analysis

From Main Menu, select Analysis > Solve or click the button.

Select Soil Nail Reinforcement

Click [OK] button to perform the analysis.

9. Analysis

Analysis > Solve

During the analysis a window will appear indicating that the solver is processing.

The analysis results are recognized as * .TA. Output files of extension *.OUT found in the working directory can be viewed in a text viewer.



10. Overview of the Analysis Results

14 Safety Factor

In the Works Tree, from Post-Works, the Factor of Safety can be viewed.

15 Max Shear Strain

By viewing the Works Tree, from Post-Works Plane-Strain Strains > Ho-Plstrn Max Shear, the max shear strain and the failure plane and be viewed.

From Ho-Plstrn, Ho represents Higher order.

Lower order is expressed as Lo-Plstrn in the post works tree.

gts 2d tutorial 18

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