Embedded Retaining Wall

Problem Statement

Note

To view this project in FLAC3D, use the menu command Help ► Examples…. The main data files used are shown at the end of this example. The remaining data files can be found in the project.

The following example illustrates the use of the embedded liner to simulate a retaining wall (e.g., a sheetpile wall). The soil/wall properties chosen for this example are for demonstration purposes; actual values for wall friction and adhesion can be found in the literature (e.g., Clayton et al. 1993).

The initial geometry for this example is shown in Figure 1.

The model uses zone initialize-stresses to initialize stresses due to gravitational loading, and the liner coupling springs are initialized with the structure liner initialize coupling command. Note that while this command accounts for the stress state in the surrounding zones, some cycling must take place to account for the gravitational weight of the liners.

The model is stepped to an equilibrium state with the embedded liner within the grid. Then the zone relax excavate command is use to excavate in a way that does not cause spurious tensile failure, and the model is stepped to equilibrium again. The resulting displacements in the soil are plotted in Figure 2. The moment distribution in the wall is shown in Figure 3.

Figure 1: Initial geometry, showing the liner embedded within the grid.

Figure 2: Displacements of the soil behind the wall.

Figure 3: \(M_y\) bending stress resultant.

Reference

Clayton, C. R. I., J. Milititsky and R. T. Woods. Earth Pressure and Earth-Retaining Structures, pp. 145-148. London: Blackie Academic & Professional (1993).

Data File

EmbeddedRetainingWall.dat

; Liner example application Embedded Retaining Wall
model new
model large-strain off
zone ratio convergence
structure ratio convergence
model title 'Demonstration of Embedded Liner'

; Create the soil.
zone create brick size 11,1,11 group 'right'
zone cmodel assign mohr-coulomb
zone property  bulk=5e9 shear=1e9 density 2000 cohesion 1e4 friction 30 tension 0
model gravity 10
; Name regions 
zone group 'left' range position-x 0 4 position-z 1 50
zone face group 'Liner' internal ...
                        range group 'right' group 'left' position-z 1.0 not
; Initial conditions
zone initialize-stresses ratio 0.6,0.4
; Boundary conditions
zone gridpoint fix velocity-x range union position-x=0 position-x=11
zone gridpoint fix velocity-y
zone gridpoint fix velocity-z range position-z=0
; create the embedded liner 
; (side1 and and side2 properties are assumed to be the same)
structure liner create by-zone-face separate range group 'Liner'
structure liner cmodel assign elastic
structure liner property young 2e9 poisson 0.25 thickness=1.0  density 2000
structure liner property coupling-stiffness-normal=1e11 ...
             coupling-stiffness-shear=1e11 coupling-yield-normal=0.0 ...
             coupling-cohesion-shear=0 coupling-cohesion-shear-residual=0 ...
             coupling-friction-shear=30.0
structure liner property coupling-stiffness-normal-2=1e11 ...
             coupling-stiffness-shear-2=1e11 coupling-yield-normal-2=0.0 ...
             coupling-cohesion-shear-2=0 ...
             coupling-cohesion-shear-residual-2=0 ...
             coupling-friction-shear-2=30.0
structure liner initialize coupling
model save 'Start'
; Solve to equilibrium
model solve
model save 'Initial'
; Excavate 
zone relax excavate range position-x 0 4 position-z 4 50
;zone null range position-x 0 4 position-z 4 50

model solve
model save 'Weaken'