Dear Prof. Masin and Soil Model Community,
I am using HP clay subroutine in Plaxis 3D to simulate soil structure interaction problem. I want void ratio and OCR variation along the depth to back analyse centrifuge test. In Plaxis, either or OCR remains constant depending on input. Moreover, I found HP subroutine in plaxis calculate void ratio without considering kheppa line. Please see details and explanations in the attached images. My objective is to obtained initial void ratio and OCR variation along the model depth. Also, I want to confirm the position of e input in parameters in ln(1+e) – lnp space. Thanks
HP clay subroutine in Plaxis
Related Articles

Using pore fluidstress element in SandSand
Kassem DibFinite Elements1 Views 3,517
Hello everyone, Is it possible to use pore fluid stress element in abaqus standard when soil is modeled using SANISAND constitutive model ? (UMAT) 
Abaqus OneAPI Compiler
Kassem DibFinite Elements1 Views 7,800
Hello.. I am testing SaniSand constitutive model as published by Mr. Masin at this site. The Abaqus is V21 and the visual studio 2017 with OneAPI compiler, the Abaqus verification […] 
UMAT code for Unsaturated soil modes
Arghya DasFinite Elements1 Views 4,156
Hello Everyone, I am trying to implement an unsaturated soil model (BBM or similar) in ABAQUS using UMAT. We want to assign a porepressure boundary condition for simulating the drying […] 
UMAT and oneAPI compiler issues. (SOLVED…i hope :p)
anis kheffacheFinite Elements7 Views 1,772
Dear all, A while ago, a person asked about the hypoplasticity umats, the problem was that the umats were not working when compiled using the oneAPI fortran compiler, an error […] 
Presentations on hypoplasticity applications, D. Mašín, NGI 2017
David MašínFinite Elements0 Views 5,179
Based on some requests, I share here two presentations on hypoplasticity applications. One is related to simulation of various boundary value problems, the other focuses on simulation of cyclic and […] 
UMAT for hypoplastic subroutine
Naif AlsanabaniFinite Elements4 Views 4,170
Hello all, Could you please anyone provide me umat for Hypoplastic model that used as subroutine in Abqus 6.14. With Best Regards Naif Mohammed 
Few more Question on calculating lateral displacement of pile using hypoplastic clay model
Muhammad AhmadFinite Elements0 Views 3,905
Dear Professor David, Thank you very much for your previous clarification. its really helps. In continuation to my previous , there are few more question, i want your kindself to […] 
Calibrate hypoplastic model
sahar saabFinite Elements2 Views 3,402
I am trying to calibrate my sand using Excalibre. I tried some triaxial element tests using Abaqus. However the results are different between Excalibre and Abaqus.
Who is Online
No one is online right now
Search SoilModels Website
Recent posts
 Drucker Prager Cap Hardening Model 20.6.2024
 Soil model for sand under drained cyclic loading 15.6.2024
 In Abaqus how do we use *DLOAD for defining both userdefined pressure and body force simultaneously? 15.6.2024
 Issue in applying SANISAND04 UMAT to BoundaryValueProblem 31.5.2024
 Triaxial compression test using MohrCoulomb model in Abaqus 27.5.2024
 The Mises stress calculated by the hypoplasticity model considering the intergranular strain is all 0 20.5.2024
 Degradation ( disturbance ) of hypoplastic clay 23.4.2024
 Degradation ( disturbance ) of hypoplastic clay 23.4.2024
 Paper of Coulomb, C. A. (1773) 15.4.2024
 ABAQUS UMAT of hypoplastic clay model 6.4.2024
 Prague Geotechnical Days 2024 “Geotechnical monitoring” and 30th jubilee Prague Geotechnical Lecture by prof. Eduardo Alonso 5.4.2024
 UMAT for CreepSCLAY model. 1.3.2024
Recent Comments
 Ashesh Choudhury on Abaqus
 Hu Shihong on Triaxial compression test using MohrCoulomb model in Abaqus
 Mert Eyupgiller on Triaxial compression test using MohrCoulomb model in Abaqus
 Bala Harsha Srusti on ABAQUS job doesn’t make any increment
 PRATIK GOEL on Hardening parameters (yield stress & absolute plastic strain)
 Ashraf AHMED on ExCalibre – SoilModels Automatic Calibration
 Xy Ma on Sand and clay standard datasets
 Xy Ma on Sand and clay standard datasets
 Ramon Varghese on Hypoplastic Interface Model: Does anybody implemented this model in FLAC3D
 Jh Xue on UMAT Implementation in Abaqus (Hypoplastic clay Subroutines)
 Santosh Katuwal on PM4Sand for Plaxis Download
 KHA DIDJA on SANISAND Abaqus UMAT and Plaxis implementations
 Debdip Das on SANISAND Abaqus UMAT and Plaxis implementations
 Ramon Varghese on SANISAND for FLAC3D Download
 Akhtyar Gul Shirzoi on ABAQUS UMAT of hypoplastic clay model
 KHA DIDJA on Animating Soil Models
 Jh Xue on Undrained Tests with Clay Hypoplasticity Intergranular
 Zhentao Liu on Problem in simulating CPT using SANISAND04
Dear Muhammad,
Actually, there are these two options only, initialise through constant void ratio or constant OCR. By the way, these only work with “K0 initilisation procedure”. With gravity loading procedure, void ratio will redictribute during gravity loading. If you need more complex distribution of void ratio with depth, you will have to approximate it through using many soil layers which will have the same parameters, just different initial void ratio.
Regards David
Dear Prof. Masin,
Thanks for your reply.
May I know how the model calculate undrained shear strength (cu)? Is it based on initial void ratio like critical state frame work or some other way? My concern is, if void ratio is constant along the model depth how can we obtained increasing cu along the depth with increasing effective stresses having constant void ratio?
Thanks for your help.
Regards,
Muhammad
Hi Muhammad,
Yes, HP model calculates cu based on the critical state soil mechanics framework. If you set constant void ratio with depth, you get constant undrained shear strength with depth. You can either initialise OCR, than cu will be distributed over depth based on that OCR. Or, you need to define layers with different void ratios.
David
Hi both,
Does this mean that the undrained shear strength can therefore be calculated for the hypoplastic model using the same formula for the MCC model:
Su=M/2 exp^(((Γ1e)/λ))
Cheers,
Hashmi
Just with a difference that in the oridnary Modified Cam clay normal compression lines are considered as linear in p vs 1+e plane, whereas hypoplastic model adopts Butterfield’s formulation with normal compression line linear in ln(1+e) vs ln p plane, so the equation needs to be updated accordingly. David