unconsolidated undrained triaxial test
Hi all,
I have a general question, my understanding is we are modelling
"unconsolidated undrained (UU) triaxial test" through below script? is that correct ?
If yes, can we model CU ( consolidated undrained ) and CD (consolidated drained ) tests by yade as well?
Thanks for help
Seti
# -*- coding: utf-8 -*-
#******
# Copyright (C) 2010 by Bruno Chareyre *
# bruno.chareyre_
# *
# This program is free software; it is licensed under the terms of the *
# GNU General Public License v2 or later. See file LICENSE for details. *
#******
## This script details the simulation of a triaxial test on sphere packings using Yade
## See the associated pdf file for detailed exercises
## the algorithms presented here have been used in published papers, namely:
## * Chareyre et al. 2002 (http://
## * Chareyre and Villard 2005 (https:/
## * Scholtès et al. 2009 (http://
## * Tong et al.2012 (http://
##
## Most of the ideas were actually developped during my PhD.
## If you want to know more on micro-macro relations evaluated by triaxial simulations
## AND if you can read some french, it is here: http://
from yade import pack,plot
#######
### DEFINING VARIABLES AND MATERIALS ###
#######
# The following 5 lines will be used later for batch execution
nRead=readParam
num_spheres=1000,# number of spheres
compFricDegree =36.28, # contact friction during the confining phase
key='_
unknownOk=True
)
from yade.params import table
num_spheres=
key=table.key
targetPorosity = 0.42 #the porosity we want for the packing
compFricDegree = 40# contact friction during the deviatoric loading
rate=-0.1 # loading rate (strain rate)
damp=0.3 # damping coefficient
stabilityThresh
young=229e6# contact stiffness
mn,mx=Vector3(
## create materials for spheres and plates
O.materials.
O.materials.
## create walls around the packing
walls=aabbWalls
wallIds=
## use a SpherePack object to generate a random loose particles packing
sp=pack.
clumps=False #turn this true for the same example with clumps
if clumps:
## approximate mean rad of the futur dense packing for latter use
volume = (mx[0]-
mean_rad = pow(0.09*
## define a unique clump type (we could have many, see clumpCloud documentation)
c1=pack.
## generate positions and input them in the simulation
sp.makeClumpCl
sp.toSimulatio
O.bodies.
else:
sp.makeCloud(
#sp.makeCloud(
O.bodies.
#or alternatively (higher level function doing exactly the same):
#sp.toSimulati
#######
### DEFINING ENGINES ###
#######
triax=TriaxialS
## TriaxialStressC
## this control of boundary conditions was used for instance in http://
maxMultiplier=
finalMaxMultip
thickness = 0,
## switch stress/strain control using a bitmask. What is a bitmask, huh?!
## Say x=1 if stess is controlled on x, else x=0. Same for for y and z, which are 1 or 0.
## Then an integer uniquely defining the combination of all these tests is: mask = x*1 + y*2 + z*4
## to put it differently, the mask is the integer whose binary representation is xyz, i.e.
## "100" (1) means "x", "110" (3) means "x and y", "111" (7) means "x and y and z", etc.
stressMask = 7,
internalCompac
)
newton=
#######
#Modified engine
#######
O.engines=[
#[Ip2_
useIncrement
always_
label=
#[Law2_
#useIncremen
#always_
#label=
),
## We will use the global stiffness of each body to determine an optimal timestep (see https:/
triax,
newton
]
#######
#O.engines=[
#ForceResetter(),
#InsertionSort
#InteractionLoop(
#[Ig2_
#[Ip2_
#[Law2_
#),
## We will use the global stiffness of each body to determine an optimal timestep (see https:/
#GlobalStiffne
#triax,
#TriaxialState
#newton
#]
#######
#Display spheres with 2 colors for seeing rotations better
Gl1_Sphere.
if nRead==0: yade.qt.
## UNCOMMENT THE FOLLOWING SECTIONS ONE BY ONE
## DEPENDING ON YOUR EDITOR, IT COULD BE DONE
## BY SELECTING THE CODE BLOCKS BETWEEN THE SUBTITLES
## AND PRESSING CTRL+SHIFT+D
#if nRead==0: yade.qt.
print 'Number of elements: ', len(O.bodies)
print 'Box Volume: ', triax.boxVolume
#######
### APPLYING CONFINING PRESSURE ###
#######
#the value of (isotropic) confining stress defines the target stress to be applied in all three directions
triax.goal1=
#while 1:
#O.run(1000, True)
##the global unbalanced force on dynamic bodies, thus excluding boundaries, which are not at equilibrium
#unb=
#print 'unbalanced force:',unb,' mean stress: ',triax.meanStress
#if unb<stabilityTh
#break
#O.save(
#print "### Isotropic state saved ###"
#######
### REACHING A SPECIFIED POROSITY PRECISELY ###
#######
### We will reach a prescribed value of porosity with the REFD algorithm
### (see http://
### http://
import sys #this is only for the flush() below
while triax.porosity>
## we decrease friction value and apply it to all the bodies and contacts
compFricDegree = 0.95*compFricDegree
setContactFric
print "\r Friction: ",compFricDegree," porosity:
sys.stdout.flush()
## while we run steps, triax will tend to grow particles as the packing
## keeps shrinking as a consequence of decreasing friction. Consequently
## porosity will decrease
O.run(500,1)
O.save(
print "### Compacted state saved ###"
#######
### DEVIATORIC LOADING ###
#######
##We move to deviatoric loading, let us turn internal compaction off to keep particles sizes constant
triax.internalC
## Change contact friction (remember that decreasing it would generate instantaneous instabilities)
setContactFrict
##set stress control on x and z, we will impose strain rate on y
triax.stressMask = 5
##now goal2 is the target strain rate
triax.goal2=rate
## we define the lateral stresses during the test, here the same 10kPa as for the initial confinement.
triax.goal1=-150000
triax.goal3=-150000
##we can change damping here. What is the effect in your opinion?
newton.damping=0.1
###########
##############
############
###########
##Save temporary state in live memory. This state will be reloaded from the interface with the "reload" button.
O.saveTmp()
#######
### Example of how to record and plot data ###
#######
#from yade import plot
### a function saving variables
def history():
plot.
s11=
s22=
s33=
i=O.iter)
if 1:
## include a periodic engine calling that function in the simulation loop
O.engines=
##O.engines.
else:
## With the line above, we are recording some variables twice. We could in fact replace the previous
## TriaxialRecorder
## by our periodic engine. Uncomment the following line:
O.engines[
O.run(100,True)
### declare what is to plot. "None" is for separating y and y2 axis
#plot.plots=
### the traditional triaxial curves would be more like this:
#plot.plots=
plot.plots=
## display on the screen (doesn't work on VMware image it seems)
plot.plot()
##### PLAY THE SIMULATION HERE WITH "PLAY" BUTTON OR WITH THE COMMAND O.run(N) #####
## In that case we can still save the data to a text file at the the end of the simulation, with:
plot.saveDataTx
##or even generate a script for gnuplot. Open another terminal and type "gnuplot plotScriptKEY.
plot.saveGnuplo
rr=yade.
rr.shape=False
rr.intrPhys=True
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