Issues with pile cmodel mohr-coulomb assignment and verification in Laterally Loaded Pile FLAC3D model

FLAC3D
1

Hello,

I am working on a FLAC3D model of a laterally loaded pile LaterallyLoaded.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

    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