# Invalid elements in liner elements
**URL:** https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278
**Category:** FLAC3D
**Created:** [November 18, 2025, 2:43pm UTC](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278 "2025-11-18T14:43:11Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)
#### Post date: [November 18, 2025, 2:43pm UTC](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278/1 "2025-11-18T14:43:11Z")
Hi Itascans, I have installed a lining in the excavation of a shaft (146 ft diameter) using liner elements; however, when checking the internal forces, none are calculated because it reports that I have many invalid elements. It seems like something very simple that is failing — any ideas?
Thanks.
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### Author:  [@cheng](https://forum.itascainternational.com/u/cheng)
#### Post date: [November 18, 2025, 3:54pm UTC](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278/2 "2025-11-18T15:54:41Z")
Because in your plot there are some elements whose normal directions are align with your set SurfX (1,0,0). The default local Z-axis is along the element normal direction so the local X-axis (SurfX) cannot be the same direction.
We have two methods to void this:
(1) Do not plot those elements with the above issue. This can be done by (a) uncheck or (b) using interactive range tool.
(2) adjust SurfX. A good practice is to to set it to the direction of tunnel axis.
Sometimes we need to combine the above two.
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### Author:  [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)
#### Post date: [November 20, 2025, 4:58pm UTC](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278/3 "2025-11-20T16:58:39Z")
Thank you, Cheng, for your help. As you mentioned, It was actually a simple issue related to the post-processing and the plotting, not the model itself. Problem solved!