I want to establish a circular retaining structure with a buried depth of 1.5m, so in phase 1, I deactivated the soil with a diameter of 10m and activated the circular retaining structure. I can understand the uplift of the soil inside the enclosure structure, but why does the soil outside the enclosure structure also swell ? Who can tell me some possible reasons, I would be very grateful to you.
Similar question posted here:Piled Raft FoundationThe structure is connected to the surrounding soil via the interface element. Therefore you should expect that depending on the level of bondage that the soil would follow the movement of the structure.
Hi，
Do you mean that the upward movement of the concrete structure causes the upward movement of the surrounding soil? But in my model, I'm not putting any force on the concrete structure. I do not believe that the concrete structure can move upward due to the unloading rebound of the soil.
There are many obvious causes for the uplift that I presume you have already investigated?
You can always send your project to our support department to have a further look.
With kind regards,
Dennis Waterman
Thank you for your reply.
First of all, I used the interface in all models and the soil was normally consolidated. The unit weight of the wall is 25, and the unit weight of the soil is 18. I have made quite a few attempts according to your suggestions.1) By increasing the ratios Eur/E50 and Eur/Eoed, the uplift value of the concrete wall does decrease, but the reduction is small enough to be negligible.2) By testing HSS, HS and MC respectively, the results of wall uplift are Uz (MC) >Uz (HS) >Uz (HSS).
However, no matter how it is changed, the soil and the wall will settle during the installation of the wall (which is reasonable). But during excavation, the walls always uplift. For example, during the installation phase, the total displacement UZ=-2mm, and then during the excavation phase, the total displacement UZ=0.1mm.
In fact, I just want to understand how to avoid this kind of situation in the program that is impossible to happen in real engineering.
I have to give up now, I found that soil uplift is impossible to change.
I'm sure there is a simple explanation and solution for it. That is why I suggested to send the project to our support department, which I presume you haven't done yet.
This is a fairly simple model. I really want to know what the problem is and how to modify it so that the soil does not uplift. Here is the command flow.
##~ running Plaxis3DInput.exe 22.1.0.452_setproperties "Title" "" "Company" "only@ ::LAVteam::®" "Comments" "" "UnitForce" "kN" "UnitLength" "m" "UnitTime" "day" "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" "Full" "ElementType" "10-Noded"_initializerectangular SoilContour -150 -150 150 150_borehole 0 0_set Borehole_1.Head -0.5_soillayer 0_soilmat "SoilModel" "Mohr-Coulomb"_set SoilMat_1.SoilModel "HS small"_set SoilMat_1.Identification "soil"_set Soil.DrainageType "Undrained A"_set Soil.gammaUnsat 18_set Soil.gammaSat 18.6_set Soil.E50Ref 5000_set Soil.G0Ref 45000_set Soil.gamma07 0.0002_set Soil.cRef 10_set Soil.phi 20_set Soil.InterfaceStrengthDetermination "Manual"_set Soil.Rinter 0.7_set Soillayer_1.Zones[0].Bottom -150_set Soillayer_1.Soil.Material Soil_gotostructures_gotosoil_soilmat "SoilModel" "Mohr-Coulomb"_set SoilMat_1.SoilModel "Linear Elastic"_set SoilMat_1.Identification "concrete"_set Concrete.gammaUnsat 25_set Concrete.gammaSat 25_set Concrete.DrainageType "Non-porous"_set Concrete.ERef 30000000_set Concrete.nu 0.2_gotostructures_polycurve 0 0 0 1 0 0 0 1 0_reset Polycurve_1 "Arc" 0 180 6 "Arc" 0 180 6_set Polycurve_1.Offset2 -6_polycurve 0 0 0 1 0 0 0 1 0_reset Polycurve_2 "Arc" 0 180 6.4 "Arc" 0 180 6.4_set Polycurve_2.Offset2 -6.4_surface -8 8 0 9 8 0 9 -8 0_addpoint Polygon_1 -10 -7 0_intersect (Polygon_1 Polycurve_2 Polycurve_1)_delete (Surface_3)_extrude (Surface_1 Surface_2) 0 0 -1.5_delete Geometry (Surface_1 Surface_2)_decomposesrf Volume_1_delete Geometry (Surface_Volume_1_3 Surface_Volume_1_4)_delete Geometry Surface_Volume_1_1_delete Geometry Surface_Volume_1_6_posinterface (Surface_Volume_1_5 Surface_Volume_1_2)_delete Geometry (Polycurve_6 Polycurve_5 Polycurve_4 Polycurve_3)_gotomesh_refine (BoreholeVolume_1_Volume_1_1 BoreholeVolume_1_Volume_2_1)_mesh "Coarseness" 0.05 "UseEnhancedRefinements" True "EMRGlobalScale" 1.2 "EMRMinElementSize" 0.005 "UseSweptMeshing" False_gotostages_phase InitialPhase_set Model.CurrentPhase Phase_1_set Soil_1_Soil_2_1.Material Phase_1 Concrete_activate Interfaces Phase_1_phase Phase_1_set Model.CurrentPhase Phase_2_set Model.CurrentPhase Phase_1_set Model.CurrentPhase Phase_2_deactivate (Soil_1_Soil_3_1) Phase_2
I'm sorry to say, but the forum is not for support cases but to answer general questions. Support cases must be sent in through https://bentleysystems.service-now.com/csp