# P2P Sand Model and Free-Field Boundary

**URL:** https://forum.itascainternational.com/t/p2p-sand-model-and-free-field-boundary/1355
**Category:** FLAC3D
**Created:** [March 5, 2024, 9:24am UTC](https://forum.itascainternational.com/t/p2p-sand-model-and-free-field-boundary/1355 "2024-03-05T09:24:59Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![cgulenc](https://avatars.discourse-cdn.com/v4/letter/c/71c47a/32.png) [@cgulenc](https://forum.itascainternational.com/u/cgulenc)
#### Post date: [March 5, 2024, 9:24am UTC](https://forum.itascainternational.com/t/p2p-sand-model-and-free-field-boundary/1355/1 "2024-03-05T09:24:59Z")

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Hi,

I want to ask a question about the wharf example given in FLAC3D website. It is seen from the following figures that P2P sand model is assigned to a region (green) surrounded by non-liquefiable soil (turquois) with Mohr-Coulomb constitutive model. It means that P2P sand model will not be employed in free-field boundary. Is the surrounding region defined intentionally? Is there any restriction about using P2P sand model as a free-field boundary element? Can we use P2P sand model for the zones along free-field boundaries?

 ![image](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/63e4fa49776bfaaef3be6d99417b713e3895f19b.jpeg)

 ![image](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/0369e19a48a6ae2c8287bb50b9bca406513f94cc.png)

Best Regards,  
CGulenc

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### Author: ![dblanksma](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@dblanksma](https://forum.itascainternational.com/u/dblanksma)
#### Post date: [March 5, 2024, 7:48pm UTC](https://forum.itascainternational.com/t/p2p-sand-model-and-free-field-boundary/1355/2 "2024-03-05T19:48:14Z")

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Hello @cgulenc,  
If the model is fully liquefied, there will be no shear resistance so the model might have overly large lateral deformation. This model is just an illustration, and we try to avoid this. If the model is **not** fully liquefied, it should be ok.

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### Author: ![cgulenc](https://avatars.discourse-cdn.com/v4/letter/c/71c47a/32.png) [@cgulenc](https://forum.itascainternational.com/u/cgulenc)
#### Post date: [March 5, 2024, 8:25pm UTC](https://forum.itascainternational.com/t/p2p-sand-model-and-free-field-boundary/1355/3 "2024-03-05T20:25:37Z")

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OK. Thank you.

Kind Regards,  
CGulenc