# UDEC v7 - Strain-softening model - elements instantly reach failure after excavation **URL:** \ **Category:** UDEC\ **Created:** [April 7, 2022, 3:57am UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417 "2022-04-07T03:57:54Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Thiru28](https://avatars.discourse-cdn.com/v4/letter/t/7ea924/32.png) [@Thiru28](https://forum.itascainternational.com/u/Thiru28)\ **Post date:** [April 7, 2022, 3:57am UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417/1 "2022-04-07T03:57:54Z")
Hi There, When I use strain-softening model in UDEC 7, the element instantly reach failure after tunnel excavation. I am modeling block as a CWFS material to simulate brittle behavior of Sandstone under high stress. A similar model parameters that I used in 3DEC did work as expected and failure zone appeared around opening where stress reached spalling limit. Please see the attached screenshots and command files for your reference. ![3D02_initial_SSII.dat|attachment (3.6 KB)EC - model](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/577f76dc5d26070620eb41243c346388bb14b20c.png) ![UDEC model](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/c6a4ebaf17bde62c9052bcb628f05fc98e0c05fc.png) I have used both small strain and large strain in the model and this procedure did not help at all. Please advise what I am missing here to simulate Strain Softening model in UDEC 7. Many thanks Thiru [02\_initial\_SSII.dat](https://forum.itascainternational.com/uploads/short-url/4Btql9LzlObPZDmmH7CskK9ZSUE.dat) (3.6 KB) ---
**Author:** ![udecsupport](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@udecsupport](https://forum.itascainternational.com/u/udecsupport)\ **Post date:** [April 7, 2022, 10:22pm UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417/2 "2022-04-07T22:22:43Z")
I would send all of the data files to [udecsupport@itascacg.com](mailto:udecsupport@itascacg.com) ---
**Author:** ![Thiru28](https://avatars.discourse-cdn.com/v4/letter/t/7ea924/32.png) [@Thiru28](https://forum.itascainternational.com/u/Thiru28)\ **Post date:** [April 22, 2022, 11:10am UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417/3 "2022-04-22T11:10:26Z")
> [@udecsupport](#): > > [udecsupport@itascacg.com](mailto:udecsupport@itascacg.com) Thanks. I have sent all files to the support team and am waiting their response. ---
**Author:** ![Kh.Mohammadamini](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/kh.mohammadamini/32/71_2.png) [@Kh.Mohammadamini](https://forum.itascainternational.com/u/Kh.Mohammadamini)\ **Post date:** [April 22, 2022, 12:04pm UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417/4 "2022-04-22T12:04:12Z")
Make sure the stresses are applied correctly. If you have very small blocks, keep them rigid. Or consider the elastic behavioral model of small groups. ---
**Author:** ![Thiru28](https://avatars.discourse-cdn.com/v4/letter/t/7ea924/32.png) [@Thiru28](https://forum.itascainternational.com/u/Thiru28)\ **Post date:** [April 25, 2022, 11:18pm UTC](https://forum.itascainternational.com/t/udec-v7-strain-softening-model-elements-instantly-reach-failure-after-excavation/417/5 "2022-04-25T23:18:09Z")
Thanks and the UDEC support team has fixed the issue in my commands as I was using a same table number for input and result and when the program runs, input table overwrites by result table.