Different results for two phase sequence approaches

Question

Hi, 
 I'm trying to reproduce the results of a publication that deals with pile test loads. Here, a displacement load is applied to the pile. However, the simulations fail depending on the phase sequence. I have tried two different approaches. First, the applied displacement on the pile was increased phase by phase. After the last phase the displacement should be 0.07m. With this approach the simulation fails in the second last phase at a displacement of 0.017m with the error message "Load advancement procedure fails. [Error code: 103]". Second I've tried to model the whole displacement in one single phase. Here the simulation runs until a displacement of 0.04m and then fails. In both approaches the resulting force starts to oscillate right before the simulation stops. In my opinion the simulation should stop at the same displacement or am I wrong? What is the difference between the two approaches and how can I reach the maximum applied displacement? I've also tried different meshes and the coarser the mesh the more likely it is that the simulation will reach the maximum displacement of 0.07m. The simulations were performed using Plaxis 2019. Enclosed the model setup with the different approaches. 
 .

Fullscreen 
 base.log 
 Download 
 
 ##~ running Plaxis2DXInput.exe 2019.0.0.0
_initializerectangular SoilContour 0 0 9 15
_setproperties "Title" "Pfahlbelastung" "Comments" "" "UnitForce" "kN" "UnitLength" "m" "UnitTime" "day" "UnitTemperature" "K" "UnitEnergy" "kJ" "UnitPower" "kW" "WaterWeight" 10 "ReferenceTemperature" 293.15 "LiquidSpecificHeatCapacity" 4181.3 "LiquidThermalConductivity" 0.0006 "LiquidLatentHeat" 334000 "LiquidThermalExpansion" 0.00021 "LiquidTemperature" 293.15 "IceSpecificHeatCapacity" 2108 "IceThermalConductivity" 0.00222 "IceThermalExpansion" 5E-5 "VapourSpecificHeatCapacity" 1930 "VapourThermalConductivity" 2.5E-5 "VapourSpecificGasConstant" 461.5 "UseTemperatureDepWaterPropsTable" False "ModelType" "Axisymmetry" "ElementType" "15-Noded"
_gotostructures
_polygon (0 0) (9 0) (9 15) (0 15)
_soilmat "Comments" "" "MaterialName" "Steifer Ton HS" "Colour" 10676870 "MaterialNumber" 2 "SoilModel" 3 "UserDefinedIndex" 0 "DrainageType" 0 "DilatancyCutOff" False "UndrainedBehaviour" 0 "InterfaceStrength" 0 "InterfaceStiffness" 0 "ConsiderGapClosure" True "K0PrimaryIsK0Secondary" True "K0Determination" 0 "SolidThermalExpansion" 1 "UnfrozenWaterContent" 0 "TableUnfrozenWaterContent" "[]" "CrossPermeability" 0 "DefaultValuesAdvanced" True "DataSetFlow" 0 "ModelFlow" 0 "UDModelFlow" 0 "SoilTypeFlow" 0 "LowerUpper" 0 "UsdaSoilType" 0 "StaringUpperSoilType" 0 "StaringLowerSoilType" 0 "M50" 0 "UseDefaultsFlow" 0 "TablePsiPermSat" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "SplinePsiPerm" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "SplinePsiSat" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "UseAlternatives" False "TensionCutOff" True "einit" 0.499999999999999 "emin" 0 "emax" 999 "SkemptonB" 0.986622073578595 "KwRefN" 3687500 "VolumetricSpecificStorage" 2.71186440677966E-6 "SolidThermalExpansionTotal" 0 "DrainageConductivity" 0 "EurRef" 90000 "ErefOed50" 0.733333333333333 "ErefUr50" 2 "Cc" 0.0104545454545454 "Cs" 0.00345 37500 0.2 20 20 0 0 0 0 20 20 0 0 1 0 0 0 0 0 0 0.333333333333333 0 0.999 0 0 0 0 1.0000000000000000E+015 0.495 0 0 0.55249663172925 1.46502579016215 0 0.5 100 67201.2715860466 0.9 33000 0.657979856674331 45000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0.8 0.8 1 0 2 -1.06 -2.37 0 0 10000 1 0.0620347394540943 3.83 1.3774 1.25 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 10 13 77 0 0 0 0 0 0 0
_soilmat "Comments" "" "MaterialName" "Pfahl" "Colour" 10283244 "MaterialNumber" 0 "SoilModel" 1 "UserDefinedIndex" 0 "DrainageType" 0 "DilatancyCutOff" False "UndrainedBehaviour" 0 "InterfaceStrength" 0 "InterfaceStiffness" 0 "ConsiderGapClosure" True "K0PrimaryIsK0Secondary" True "K0Determination" 1 "SolidThermalExpansion" 1 "UnfrozenWaterContent" 0 "TableUnfrozenWaterContent" "[]" "CrossPermeability" 0 "DefaultValuesAdvanced" True "DataSetFlow" 0 "ModelFlow" 0 "UDModelFlow" 0 "SoilTypeFlow" 0 "LowerUpper" 0 "UsdaSoilType" 0 "StaringUpperSoilType" 0 "StaringLowerSoilType" 0 "M50" 0 "UseDefaultsFlow" 0 "TablePsiPermSat" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "SplinePsiPerm" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "SplinePsiSat" "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]" "einit" 0.5 "emin" 0 "emax" 998.999999999999 "Dinter" 0 "SkemptonB" 0.986622073578595 "KwRefN" 1229166666.66667 "VolumetricSpecificStorage" 8.13559322033899E-9 "SolidThermalExpansionTotal" 0 "DrainageConductivity" 0 "Eref" 30000000 "Eoed" 33333333.3333333 "Vs" 2214.72345903501 "Vp" 3616.62826400503 "Einc" 0 12500000 0.2 0 0 0 0 0 0 25 25 0 0 1 0 0 0 0 0 0 0.333333333333333 0 0.999 0 0 0 0 1.0000000000000000E+015 0.495 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0.5 0.5 1 0 0 -1.06 -2.37 0 0 10000 1 0.0620347394540943 3.83 1.3774 1.25 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 10 13 77 0 0 0 0 0 0 0
_setmaterial (Soil_1) SteiferTonHS
_line 3 15 3 3
_line 3 3 0 3
_line 0.65 15 0.65 5.5
_line 0.65 5.5 0 5.5
_linedispl 0 15 0.65 15
_mergeequivalents Geometry
_gotomesh
_set Line_5_1.CoarsenessFactor 0.1
_set Line_4_1.CoarsenessFactor 0.1
_set Polygon_1_1.CoarsenessFactor 0.1
_set Polygon_1_2.CoarsenessFactor 0.1
_mesh 0.07998 #coarse
_selectmeshpoints
/Output acp "Node" Soil_1_1 (0 15)
/Output update
_gotostages
_activate Soils InitialPhase
_phase InitialPhase
_set Soil_1_1.Material Phase_1 Pfahl
_phase Phase_1
_set Phase_2.Deform.ResetDisplacementsToZero True
_activate (LineDisplacement_1_1) Phase_2
_set LineDisplacement_1_1.uy_start Phase_2 -0.001
_phase Phase_2
_set LineDisplacement_1_1.uy_start Phase_3 -0.002
_phase Phase_3
_set LineDisplacement_1_1.uy_start Phase_4 -0.004
_phase Phase_4
_set LineDisplacement_1_1.uy_start Phase_5 -0.008
_phase Phase_5
_set LineDisplacement_1_1.uy_start Phase_6 -0.016
_phase Phase_6
_set LineDisplacement_1_1.uy_start Phase_7 -0.03
_phase Phase_7
_set LineDisplacement_1_1.uy_start Phase_8 -0.07
_phase Phase_1
_activate (LineDisplacement_1_1) Phase_9
_set LineDisplacement_1_1.uy_start Phase_9 -0.07

Stefanos Papavasileiou · Accepted Answer

Dear Siegfried, 
 The activation of (self-)weight and loads in a Plastic phase, Consolidation phase and Fully coupled flow-deformation analysis is considered to be an out-of-balance force. In order to solve this out-of-balance, the calculation will use a linear relationship with the &Sigma;M stage multiplier to activate these new loads. This is explained in more detail in the following article: https://communities.bentley.com/products/geotech-analysis/w/plaxis-soilvision-wiki/45973/load-activation-in-time 
 That means that due to the different out-of-balance to be solved in each model the solution can be slightly different. 
 The error you encountered, according to our reference manual, mentions that there are numerical problems detected. You need to inspect the input data and the calculation results in Output to evaluate why it fails. 
 In general, in some cases, it helps to edit the numerical control parameters and edit the max load fraction per step to a lower value. You can check more details about these parameters and the impact on the analysis in our reference manual. 
 If the above does not help identify the reason for this problem, please submit a service request. 
 Then, one of our support engineers can help you in detail: https://apps.bentley.com/srmanager/ProductSupport

Different results for two phase sequence approaches

Top Replies