# FLAC3D **URL:** https://forum.itascainternational.com/c/flac3d/5.md [Latest](https://forum.itascainternational.com/latest.md) · [Categories](https://forum.itascainternational.com/categories.md) · [Tags](https://forum.itascainternational.com/tags.md) --- ## [About the FLAC3D category](https://forum.itascainternational.com/t/about-the-flac3d-category/12)
**Author:** [@jhazzard](https://forum.itascainternational.com/u/jhazzard)\ **Replies:** 0\ **Last updated:** [July 11, 2021, 2:00am UTC](https://forum.itascainternational.com/t/about-the-flac3d-category/12 "2021-07-11T02:00:23Z")
FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) is numerical modeling software for geotechnical analyses of soil, rock, groundwater, constructs, and ground support. Such analyses include engineering design,… --- ## [Spatially variable soil layers in FLAC 3D](https://forum.itascainternational.com/t/spatially-variable-soil-layers-in-flac-3d/2404)
**Author:** [@Milads](https://forum.itascainternational.com/u/Milads)\ **Replies:** 1\ **Last updated:** [August 11, 2026, 12:54pm UTC](https://forum.itascainternational.com/t/spatially-variable-soil-layers-in-flac-3d/2404 "2026-08-11T12:54:22Z")
I am working with a 3D model that has a spatially varying soil profile. What is the recommended method for assigning soil layer groups? Can soil layers be interpolated from a few 2D cross sections? Any example workflows … --- ## [Is it possible to access the python console from the non gui version of flac](https://forum.itascainternational.com/t/is-it-possible-to-access-the-python-console-from-the-non-gui-version-of-flac/1850)
**Author:** [@stephaneBeaussier](https://forum.itascainternational.com/u/stephaneBeaussier)\ **Replies:** 3\ **Last updated:** [August 3, 2026, 10:45am UTC](https://forum.itascainternational.com/t/is-it-possible-to-access-the-python-console-from-the-non-gui-version-of-flac/1850 "2026-08-03T10:45:30Z")
Hi, I use the non-gui version of flac3d with the executable fla3d\_console on a linux server that does not have a gui interface. I wanted to know if there was a way to access the python console in this version of FLAC3D… --- ## [Can a time varying external load applied to a saturated soil mass generate excess pore pressure when using Mohr-Coulomb in a coupled fluid-mechanical analysis?](https://forum.itascainternational.com/t/can-a-time-varying-external-load-applied-to-a-saturated-soil-mass-generate-excess-pore-pressure-when-using-mohr-coulomb-in-a-coupled-fluid-mechanical-analysis/2395)
**Author:** [@Sudipta](https://forum.itascainternational.com/u/Sudipta)\ **Replies:** 0\ **Last updated:** [June 15, 2026, 5:21pm UTC](https://forum.itascainternational.com/t/can-a-time-varying-external-load-applied-to-a-saturated-soil-mass-generate-excess-pore-pressure-when-using-mohr-coulomb-in-a-coupled-fluid-mechanical-analysis/2395 "2026-06-15T17:21:35Z")
Hello @everyone, @itascaYang @isaac @itsmoho\_sen @ITE @itascaYang @itasca @dafo407\_itasca @ddegagne @dblanksma @itmam I am running a coupled fluid–mechanical FLAC3D model using the Mohr-Coulomb constitutive model. I hav… --- ## [What is the impact of having tetrahedra in a FLAC3D mesh](https://forum.itascainternational.com/t/what-is-the-impact-of-having-tetrahedra-in-a-flac3d-mesh/2371)
**Author:** [@stephaneBeaussier](https://forum.itascainternational.com/u/stephaneBeaussier)\ **Replies:** 5\ **Last updated:** [June 3, 2026, 8:00am UTC](https://forum.itascainternational.com/t/what-is-the-impact-of-having-tetrahedra-in-a-flac3d-mesh/2371 "2026-06-03T08:00:59Z")
Hi, I am having a challenge with a mesh in FLAC3D 9.4 I generated in Griddle 3.0. I am solving a creep problem with a relatively complex geometry which led Griddle to generate quiet a lot of pyramid (~14% of zones) and… --- ## [Applying Time-Varying Non-Uniform Surface Pressure in FLAC3D](https://forum.itascainternational.com/t/applying-time-varying-non-uniform-surface-pressure-in-flac3d/2390)
**Author:** [@Sudipta](https://forum.itascainternational.com/u/Sudipta)\ **Replies:** 0\ **Last updated:** [June 2, 2026, 5:18pm UTC](https://forum.itascainternational.com/t/applying-time-varying-non-uniform-surface-pressure-in-flac3d/2390 "2026-06-02T17:18:27Z")
Hello everyone and Itasca support team, @itascaYang @isaac @itsmoho\_sen @ITE @Inwoo @Inu @itmam @itasca @dafo407\_itasca @dblanksma I am trying to apply a time-varying non-uniform distributed pressure on a surface in FL… --- ## [Questions About Fully Coupled Flow–Mechanical Analysis and Solution-Control Parameters in FLAC3D](https://forum.itascainternational.com/t/questions-about-fully-coupled-flow-mechanical-analysis-and-solution-control-parameters-in-flac3d/2389)
**Author:** [@Sudipta](https://forum.itascainternational.com/u/Sudipta)\ **Replies:** 0\ **Last updated:** [June 1, 2026, 3:48pm UTC](https://forum.itascainternational.com/t/questions-about-fully-coupled-flow-mechanical-analysis-and-solution-control-parameters-in-flac3d/2389 "2026-06-01T15:48:49Z")
Hello @everyone, @itascaYang @isaac @itsmoho\_sen @ITE @Inwoo @Inu @itasca @dafo407\_itasca @itascan I am planning to perform a fully coupled flow–mechanical analysis in FLAC3D. My current understanding of the command seq… --- ## [Guidance on Introducing Fluid, Biot Coupling, and Water Table for Mechanical Pore Pressure Generation in FLAC3D](https://forum.itascainternational.com/t/guidance-on-introducing-fluid-biot-coupling-and-water-table-for-mechanical-pore-pressure-generation-in-flac3d/2388)
**Author:** [@Sudipta](https://forum.itascainternational.com/u/Sudipta)\ **Replies:** 0\ **Last updated:** [May 29, 2026, 2:55am UTC](https://forum.itascainternational.com/t/guidance-on-introducing-fluid-biot-coupling-and-water-table-for-mechanical-pore-pressure-generation-in-flac3d/2388 "2026-05-29T02:55:47Z")
Hello @everyone, @itascan @itascaYang @itasca @dafo407\_itasca @itsmoho\_sen @isaac I am trying to introduce fluid behavior and Biot coupling in a FLAC3D model so that pore pressure can be generated when external loading … --- ## [Wetting Induced Deformation Simulation- Infiltration result questionable](https://forum.itascainternational.com/t/wetting-induced-deformation-simulation-infiltration-result-questionable/2381)
**Author:** [@Adams](https://forum.itascainternational.com/u/Adams)\ **Replies:** 0\ **Last updated:** [May 8, 2026, 6:53pm UTC](https://forum.itascainternational.com/t/wetting-induced-deformation-simulation-infiltration-result-questionable/2381 "2026-05-08T18:53:52Z")
Hi, I am trying to simulate a wetting induced deformation of an embankment. I used FISH function to couple the hydraulic and stress strain behavior using Modified Cam Clay as the mechanical constitutive model and hydraul… --- ## [Difficulty with staged embankment construction using Modified Cam Clay in FLAC3D (yield envelope error)](https://forum.itascainternational.com/t/difficulty-with-staged-embankment-construction-using-modified-cam-clay-in-flac3d-yield-envelope-error/2376)
**Author:** [@Adams](https://forum.itascainternational.com/u/Adams)\ **Replies:** 2\ **Last updated:** [April 21, 2026, 7:48pm UTC](https://forum.itascainternational.com/t/difficulty-with-staged-embankment-construction-using-modified-cam-clay-in-flac3d-yield-envelope-error/2376 "2026-04-21T19:48:14Z")
I am attempting to simulate a compacted highway embankment in FLAC3D following the general framework for unsaturated hydro-mechanical behavior of compacted fill. My workflow involves staged construction of the embankment… --- ## [Delete zone/gridpoints extra](https://forum.itascainternational.com/t/delete-zone-gridpoints-extra/965)
**Author:** [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\ **Replies:** 9\ **Last updated:** [April 17, 2026, 5:11pm UTC](https://forum.itascainternational.com/t/delete-zone-gridpoints-extra/965 "2026-04-17T17:11:25Z")
Hello, I am trying to delete zone and gridpoints information stored in extra variables in order to get the file slighter but I do not find a Fish or FLAC command to achieve that, any help? Thank you in advance. --- ## [Benchmark Test, Dual CPU, Low performance](https://forum.itascainternational.com/t/benchmark-test-dual-cpu-low-performance/1163)
**Author:** [@cgulenc](https://forum.itascainternational.com/u/cgulenc)\ **Replies:** 9\ **Last updated:** [April 2, 2026, 6:19pm UTC](https://forum.itascainternational.com/t/benchmark-test-dual-cpu-low-performance/1163 "2026-04-02T18:19:12Z")
Hi, I made some static and dynamic analyses of an embankment and a benchmark test eventually. The results are not satisfactory. I believe that there is a problem, but I cannot understand. I need some help. I prepared a … --- ## [Compression Strength for Shell elements](https://forum.itascainternational.com/t/compression-strength-for-shell-elements/2313)
**Author:** [@MiguelN](https://forum.itascainternational.com/u/MiguelN)\ **Replies:** 1\ **Last updated:** [February 12, 2026, 9:32pm UTC](https://forum.itascainternational.com/t/compression-strength-for-shell-elements/2313 "2026-02-12T21:32:26Z")
Is it possible to limit the compressive strength of shell elements in order to define fc′​ for concrete simulation? Using the MC model for shell elements, the shear strength and tensile strength can be limited; however,… --- ## [Is there any way to apply acceleration history to structural nodes?](https://forum.itascainternational.com/t/is-there-any-way-to-apply-acceleration-history-to-structural-nodes/742)
**Author:** [@ppk](https://forum.itascainternational.com/u/ppk)\ **Replies:** 2\ **Last updated:** [January 22, 2026, 12:03pm UTC](https://forum.itascainternational.com/t/is-there-any-way-to-apply-acceleration-history-to-structural-nodes/742 "2026-01-22T12:03:23Z")
I’m trying to find natural period of structures constructed with beam and shell elements. Sweeping test which applies sinusoidal waves with increasing frequencies is planned but I can’t find any way to apply (displaceme… --- ## [Query about Rayleigh Damping Parameters in FLAC3D](https://forum.itascainternational.com/t/query-about-rayleigh-damping-parameters-in-flac3d/2299)
**Author:** [@MiguelN](https://forum.itascainternational.com/u/MiguelN)\ **Replies:** 5\ **Last updated:** [January 22, 2026, 4:21am UTC](https://forum.itascainternational.com/t/query-about-rayleigh-damping-parameters-in-flac3d/2299 "2026-01-22T04:21:53Z")
How can I query FLAC3D, version 7 or 9, to obtain the Rayleigh damping parameters (specially about alpha & beta), either through FISH or from the command line? Thanks in advance --- ## [Interpreting FOS results with fault interfaces in FLAC3D](https://forum.itascainternational.com/t/interpreting-fos-results-with-fault-interfaces-in-flac3d/2284)
**Author:** [@Luca86](https://forum.itascainternational.com/u/Luca86)\ **Replies:** 5\ **Last updated:** [January 21, 2026, 12:45pm UTC](https://forum.itascainternational.com/t/interpreting-fos-results-with-fault-interfaces-in-flac3d/2284 "2026-01-21T12:45:43Z")
Hi everyone, I am currently running a model of an open pit with faults using FLAC3D v7. The geological units were imported as DXF files, while the faults were added as planar structures via Griddle and defined as interf… --- ## [How to access zone joint contacts via FISH/Python](https://forum.itascainternational.com/t/how-to-access-zone-joint-contacts-via-fish-python/2310)
**Author:** [@LeoBBL](https://forum.itascainternational.com/u/LeoBBL)\ **Replies:** 2\ **Last updated:** [January 7, 2026, 11:32pm UTC](https://forum.itascainternational.com/t/how-to-access-zone-joint-contacts-via-fish-python/2310 "2026-01-07T23:32:50Z")
Hi everyone, I’m trying to find a way to access to zone joint contact variables either via FISH or Python (e.g., get/set properties, displacements, state, extras, etc). I haven’t found any guidance in the available docu… --- ## [Clarification on CDP Calibration and Peak Stress in FLAC3D Uniaxial Compression Tests](https://forum.itascainternational.com/t/clarification-on-cdp-calibration-and-peak-stress-in-flac3d-uniaxial-compression-tests/2308)
**Author:** [@MojtabaNematollahi](https://forum.itascainternational.com/u/MojtabaNematollahi)\ **Replies:** 0\ **Last updated:** [December 16, 2025, 12:32pm UTC](https://forum.itascainternational.com/t/clarification-on-cdp-calibration-and-peak-stress-in-flac3d-uniaxial-compression-tests/2308 "2025-12-16T12:32:14Z")
Dear Zhao Cheng, Based on the CDP concrete model, the stress obtained in a uniaxial compression test should be scaled by the factor (1−D), where D is the damage variable. Consequently, the nominal (real) stress cannot r… --- ## [Correct Way to Represent a Pumping Well in FLAC3D?](https://forum.itascainternational.com/t/correct-way-to-represent-a-pumping-well-in-flac3d/2306)
**Author:** [@Wenjie](https://forum.itascainternational.com/u/Wenjie)\ **Replies:** 2\ **Last updated:** [December 12, 2025, 1:26am UTC](https://forum.itascainternational.com/t/correct-way-to-represent-a-pumping-well-in-flac3d/2306 "2025-12-12T01:26:49Z")
Hello, I am simulating a pumping scenario, and my procedure is as follows: 1. I use a command to search for the grid points around the well (using range cylinder). Suppose the total number of selected grid points … --- ## [Request for Guidance on Plastic Multiplier Calculation for Constitutive Model in FLAC3D](https://forum.itascainternational.com/t/request-for-guidance-on-plastic-multiplier-calculation-for-constitutive-model-in-flac3d/2173)
**Author:** [@MojtabaNematollahi](https://forum.itascainternational.com/u/MojtabaNematollahi)\ **Replies:** 7\ **Last updated:** [December 2, 2025, 2:32am UTC](https://forum.itascainternational.com/t/request-for-guidance-on-plastic-multiplier-calculation-for-constitutive-model-in-flac3d/2173 "2025-12-02T02:32:12Z")
Dear Colleagues, I am currently developing a new constitutive model that incorporates a curved yield surface, conceptually similar to the Drucker-Prager criterion. My current challenge lies in determining the plastic mu… --- ## [Mesh and zone quality checks](https://forum.itascainternational.com/t/mesh-and-zone-quality-checks/297)
**Author:** [@ALG](https://forum.itascainternational.com/u/ALG)\ **Replies:** 8\ **Last updated:** [December 1, 2025, 4:11pm UTC](https://forum.itascainternational.com/t/mesh-and-zone-quality-checks/297 "2025-12-01T16:11:35Z")
Hello all, Does anyone want to share their zone/mesh quality checking routine? A process to highlight poor zones that may cause issues for the model to solve. I guess the obvious one is the zone.test.quality command, w… --- ## [Efficient way of getting face groups in python scripts](https://forum.itascainternational.com/t/efficient-way-of-getting-face-groups-in-python-scripts/2289)
**Author:** [@stephaneBeaussier](https://forum.itascainternational.com/u/stephaneBeaussier)\ **Replies:** 1\ **Last updated:** [November 25, 2025, 4:40pm UTC](https://forum.itascainternational.com/t/efficient-way-of-getting-face-groups-in-python-scripts/2289 "2025-11-25T16:40:41Z")
Hi, I am trying to extract in python a face boundary, to track certain properties over the face. To do that I first need to get the pointer to the faces that compose this boundary (the zone pointer and face index pair … --- ## [Relative between FLAC3D zone indexes and zonearray index](https://forum.itascainternational.com/t/relative-between-flac3d-zone-indexes-and-zonearray-index/2281)
**Author:** [@stephaneBeaussier](https://forum.itascainternational.com/u/stephaneBeaussier)\ **Replies:** 5\ **Last updated:** [November 21, 2025, 11:57am UTC](https://forum.itascainternational.com/t/relative-between-flac3d-zone-indexes-and-zonearray-index/2281 "2025-11-21T11:57:48Z")
Hi, I have questions about the relation between the ids of zones and faces within FLAC and the indexing in the python numpy interface: What is the relation between the index of zones and the indexing within zonearray… --- ## [Invalid elements in liner elements](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278)
**Author:** [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\ **Replies:** 2\ **Last updated:** [November 20, 2025, 4:58pm UTC](https://forum.itascainternational.com/t/invalid-elements-in-liner-elements/2278 "2025-11-20T16:58:39Z")
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 elem… --- ## [Cable model grout-rock interface](https://forum.itascainternational.com/t/cable-model-grout-rock-interface/2272)
**Author:** [@Carlos\_Mora](https://forum.itascainternational.com/u/Carlos_Mora)\ **Replies:** 4\ **Last updated:** [November 20, 2025, 9:55am UTC](https://forum.itascainternational.com/t/cable-model-grout-rock-interface/2272 "2025-11-20T09:55:49Z")
Hello Itascans! We are seeking your help with the performance results of bolts installed in a shaft model. The cable model fails predominantly along the grout–rock interface, showing a pull-out type failure, while the b… --- ## [Structural Connection Between Concrete Liner and Concrete Volume Elements](https://forum.itascainternational.com/t/structural-connection-between-concrete-liner-and-concrete-volume-elements/2275)
**Author:** [@jng](https://forum.itascainternational.com/u/jng)\ **Replies:** 1\ **Last updated:** [November 17, 2025, 7:18pm UTC](https://forum.itascainternational.com/t/structural-connection-between-concrete-liner-and-concrete-volume-elements/2275 "2025-11-17T19:18:10Z")
Hi everyone, Does anyone have any suggestions / solution on how to model the structural connection between a liner and volume elements for some concrete structures e.g. basement slab modelled as liner element and connec… --- ## [Axial force and moment in zones](https://forum.itascainternational.com/t/axial-force-and-moment-in-zones/2270)
**Author:** [@Ahmed\_Alsadah](https://forum.itascainternational.com/u/Ahmed_Alsadah)\ **Replies:** 1\ **Last updated:** [November 12, 2025, 6:59pm UTC](https://forum.itascainternational.com/t/axial-force-and-moment-in-zones/2270 "2025-11-12T18:59:31Z")
I am modelling a rigid inclusion (pile) using zones (not structural elements), how can i get the axial force and moment for it? --- ## [Asymmetry in Stress Resultants while Joining Two Liners](https://forum.itascainternational.com/t/asymmetry-in-stress-resultants-while-joining-two-liners/2267)
**Author:** [@acGC](https://forum.itascainternational.com/u/acGC)\ **Replies:** 2\ **Last updated:** [November 7, 2025, 5:51pm UTC](https://forum.itascainternational.com/t/asymmetry-in-stress-resultants-while-joining-two-liners/2267 "2025-11-07T17:51:36Z")
Hello, everyone. I try to model a circular tunnel with different liner IDs in one ring and the idea is to connect them with deformable links. My approach is to create links on side 2 to connect two liners with different… --- ## [Assigning zone properties from boreholes like SPT, CPT, etc. for creating own 3D soil layers](https://forum.itascainternational.com/t/assigning-zone-properties-from-boreholes-like-spt-cpt-etc-for-creating-own-3d-soil-layers/2263)
**Author:** [@ace](https://forum.itascainternational.com/u/ace)\ **Replies:** 4\ **Last updated:** [November 6, 2025, 10:39pm UTC](https://forum.itascainternational.com/t/assigning-zone-properties-from-boreholes-like-spt-cpt-etc-for-creating-own-3d-soil-layers/2263 "2025-11-06T22:39:25Z")
Can anyone give me idea as to how I can import my borehole data in terms of X,Y,Z, and Nspt or qt, fs, or u2 or any other data to assign to the zones. So that I can calculate the material parameters using empirical corre… --- ## [Joining Two Liner Elements with Deformable Links](https://forum.itascainternational.com/t/joining-two-liner-elements-with-deformable-links/2264)
**Author:** [@jng](https://forum.itascainternational.com/u/jng)\ **Replies:** 1\ **Last updated:** [November 4, 2025, 8:09pm UTC](https://forum.itascainternational.com/t/joining-two-liner-elements-with-deformable-links/2264 "2025-11-04T20:09:28Z")
I’m currently working on a problem modelling an interface (e.g. waterproofing layer) between primary and secondary tunnel linings modelled using liner elements. the modelling process i’ve tried is as follows: create p… [Next page](https://forum.itascainternational.com/c/flac3d/5.md?page=1)