node-node connect between soil-segmented tunnel

[Zhou_Jx]

Dear STKO,

I want to do a seismic analysis for a segmented tunnel using STKO in a plane strain condition. The segmented tunnel is composed of six segments and six joints. The former part is simulated using elastic beam element, and the later part is simulated by the zerolength-rotational spring element. The soil domain is simulated with the quard element. Now, I want to define a slip contact between the soil domain and tunnel interface via the ZeroLengthContactASDimplex Element. I think a nodo to node link is proper to defined the tunnel-soil interaction. However, I found the tunnel contains six more nodes than soil interface, and the six nodes cannot connect with the soil interface, as shown below:

Tunnel-soil interface.jpg (41.93 KiB) Viewed 403 times

Now, I defined the interface via manually modify the exported tcl, it is inefficient. Can you give me some suggestions to define the tunnel-soil interation in STKO? Should I redefine the geometry or apply other methods?

Here is the STKO file:

Tunnel-soil interaction.zip

(224.65 KiB) Downloaded 6 times

Best regards,

Jiaxing Zhou

[STKO Team]

The basic rule in the node-node interaction is that:
Each slave node is connected to the nearest master node

This means that each slave (secondary) node will be connected to a master (primary), but not all masters will be necessarily connected to a slave!

Using this rule, you can simply make the tunnel the slave. In this way, all of its nodes will be connected.

Here I simply moved one segment to visually show this behavior.
With the tunnel as master, you have this:

S1.png (52.16 KiB) Viewed 345 times

Now you can swap master and slaves:

S2.png (15.49 KiB) Viewed 345 times

And you will have this:

S3.png (22.79 KiB) Viewed 345 times

[Zhou_Jx]

Dear STKO,

Firstly, thanks for your reply. And I have a question about the excavation analysis for the segmented tunnel buired in sand profiles.

Specifically, the soil domain is simulated using PDMY 02 soil, and the tunnel lining is simulated using beam element, as well as the tunnel-soil interface is simulated via zerolength contact implex element. What should I do to define the excavation process?

In your webinar, you have introduce the excavation analysis for pile-soil system, which inspired me very well. However, there are still some questions confused me.

1. In your webinar, a linear-ealstic soil properties is adopted to simulate the soil behavior, while I hope to do a analysis in the elastoplastic condition. Should I do the plastic analysis before the excavation or after the excavation?

2. is it properity to neglect the self-weight of tunnel?

Could you give me some advies？

Here is my model:

Excavation-tunnel-seismic.zip

(474.43 KiB) Downloaded 5 times

Best reagrds,

Jiaxing

[STKO Team]

1. In your webinar, a linear-ealstic soil properties is adopted to simulate the soil behavior, while I hope to do a analysis in the elastoplastic condition. Should I do the plastic analysis before the excavation or after the excavation?

The approach is the same. Do the plastic before the excavation, just after a first gravity analysis so that the initial stress condition is set.

2. is it properity to neglect the self-weight of tunnel?

It's up to you to understand if something is negligible or not in your model

[Zhou_Jx]

Thanks for your reply!

[ValentinaSB]

You are welcome

Best,
STKO Team