Hello,
My problem concerns the validation of oedometer tests.I run some incremental loading oedometer tests on medium stiff clays and simulated them in Plaxis using different soil models (SSC, hardening soil, MCC).I followed the procedure explained at page 192 of the Material Models Manual and considered a point on the top.The final compression curve (stress - void ratio) matches quite well with the laboratory curve, but the entire simulated curve is shifted downwards.The first load step, when simulated in Plaxis, returns much higher deformation than the laboratory results. Modifying the soil model or the stiffness values or the preconsolidation stress does not solve the problem.Another publication shows the same offset of the compression curve (Asad, 2016, Prediction of One-Dimensional Compression Test using Finite Elements Model).
I wander why this happens.
Thanks
Dear Elena,
This might be caused due to the fact that SoilTest starts with zero stresses, so the first load step applied can generate large volume strains, as the stiffness is based on that stress state.
In reality, the initial stresses can be low, but not zero, so the volume strains are typically smaller.
One suggestion would be to use smaller steps to simulate better the initial stresses or use the General tab which nowadays allows you to control better the initial stresses of the test. A comparison with zero load and a small load might point to the reason why the Oedometer test gives this difference in results.
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