Tunnel Lining Model

Intro

Create midas civil model for tunnel lining analysis.

Based on the imported elements in the DXF file, create a new node, calculate the subgrade modulus, and connect it with an elastic link(compression only).

For the spring modulus, apply the AFTES, U.S equation according to conrete lining detailed design criteria(Korea Highway Administration 2016)

Version

Applicable Standards

Benefits of this plugin

For tunnel lining anlysis, we import a DXF file (lining centerline) into midas Civil, then calculate the spring stiffness with subgrade modulus.

This plugin automatically creates nodes at a distance of 1 meter from each elements. it also calculates the subgrade modulus using AFTES formula by considering ground modulus and poisson ratio.

For the end boundary condition, we support Hinge and Spring models. For spring model, we calculate the spring stiffness by considering the cross sectional size of the element.

How to use this plugin?

To use this plugin, we need to inmport a DXF file(tunnel lining centerlines) into midas Civil.

If the element does not have an assigned section, the end boundary condition must be created with Hinge; To calculate spring stiffness, we need the width of the element.

1. Selected Elements
   After selecting the elements in MIDAS Civil for which you want to create tunnel lining model, click on the plugin to enter the elements.

2. Subgrade Modulus
   Enter the factors to calculate the spring stiffness. Enter the ground modulus and poisson’s ratio, and calculate Ks according to AFTES equation.

3. End Boundary Condition
   End boundary conditions can be modeled with Hinge and Spring.
   The creation method for each condition is as follows;
   Hinge : A Hinge boundary condition is created at the end nodes. The boundary condition is created regardless of the section assignment.
   Spring : A elastic link(compression only) is created along the lining axis. The spring stiffness is calculated based ont the width of the element.

4. Create
   Created lining model. Create a nodal point at a distance of 1m, taking into account the normal direction vector of each element. Connect that node and original node with compression only elastic link.

Note

Note that the spring boundary condition at the end can only be calculated if the element has a section assigned to it.

Conclusion

This plugin allows you to generate tunnel lining model files with boundary conditions.