# Issues with pile cmodel mohr-coulomb assignment and verification in Laterally Loaded Pile FLAC3D model **URL:** \ **Category:** FLAC3D\ **Created:** [August 15, 2025, 1:40pm UTC](https://forum.itascainternational.com/t/issues-with-pile-cmodel-mohr-coulomb-assignment-and-verification-in-laterally-loaded-pile-flac3d-model/2207 "2025-08-15T13:40:49Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![musicinquark](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/musicinquark/32/938_2.png) [@musicinquark](https://forum.itascainternational.com/u/musicinquark)\ **Post date:** [August 15, 2025, 1:40pm UTC](https://forum.itascainternational.com/t/issues-with-pile-cmodel-mohr-coulomb-assignment-and-verification-in-laterally-loaded-pile-flac3d-model/2207/1 "2025-08-15T13:40:49Z")
Hello, I am working on a FLAC3D model of a laterally loaded pile [LaterallyLoaded.dat](https://forum.itascainternational.com/uploads/short-url/xEqhhYeJkV4Va9RVAQ70OVP3UD4.dat) (4.3 KB) and trying to assign a constitutive model (cmodel) to the pile structure for verification purposes. The project file is named “LaterallyLoaded.prj”. Despite following typical procedures for cmodel assignment (using Mohr-Coulomb with plastic integration and circular cross-section), I am obtaining unexpected or non-physical results during verification runs. Key points of my setup: - Pile created by line with segments - cmodel assigned with plastic integration and circular cross-section layout - Material properties: E=80 GPa, nu=0.3, cohesion very high, friction angle 36 degrees - Coupling properties set for pile-soil interface - Boundary conditions applied on model boundaries (velocity-normal fixed) - Gravity and initial stresses initialized - Small velocity increments applied to top node group to simulate lateral loading - Model cycles run with monitoring of lateral displacement and shear force histories I suspect there might be an error or omission in the cmodel assignment or coupling property definitions, or possibly in the boundary condition groups. Has anyone successfully implemented a laterally loaded pile model with similar settings? Could you share insights or example scripts? Any suggestions on debugging or verification steps would be appreciated. Thank you in advance! [global d, b, R, ny, nz, nr, ntheta] ; ============================================================================= ; Material properties and dimensions (RC, SI units) [global E = 80e9] [global nu = 0.30] [global sigY = 250e6] [global XCrect = true] [global momCap = false] ; use moment capacity [global L = 1000e-3] [global d = 2800e-3] [global b = 800e-3] [global R = 1000e-3] ; Properties of mesh and integration layout [global nseg = 16] ; even number [global nx = 2] [global ny = 12] [global nz = 2] [global nr = 8] [global ntheta = 7] ; ===================== ; ======================================================= ; Create a pile in the center of the soil block structure pile create by-line (5.5,5.5,12.0) (5.5,5.5,4.0) segments=16 structure node group ‘Top’ range position-z 12 ; Tag top node ```auto structure pile cmodel assign mohr-coulomb structure pile cmodel plastic-integration cross-section circular [R] ... layout [nx] [nr] [ntheta] structure pile property direction-y (1,1,0) structure pile property young [E] poisson [nu] ... cohesion 3e6 friction 36 ``` structure pile property coupling-stiffness-shear=1.3e11 coupling-cohesion-shear=1.0e10 … coupling-friction-shear=0.0 coupling-stiffness-normal=1.3e09 … coupling-cohesion-normal=1.0e04 coupling-friction-normal=0.0 … coupling-gap-normal=off … ;direction-y=(1,1,0) ; so that shear force Fy corresponds with diagonal direction