Title

Sand Hypoplasticity (von Wolffersdorff, 1996)

Description

Sand hypoplasticity is an advanced incrementally non-linear constitutive model, an outcome of an extensive research at Karlsruhe University in 1990’s. It incorporates pressure- and density-dependency of soil behaviour. Its response has been validated using a number single and finite element simulations of various geotechnical problems. When combined with so-called intergranular strain concept (Niemunis and Herle, 1997), it is capable of predicting small strain stiffness degradation and cyclic loading effects.

References







Simulation Software Offering This Model

Calibration Software Offering This Model

Related Downloads

Image Gallery

Related SoilModels Forum Posts

Tags:
4 Comments
  1. Gerrard Steven
    Gerrard Steven 10 months ago

    When using this model,what is the value of the state variable?

  2. Piotr Kowalczyk
    Piotr Kowalczyk 5 months ago

    Dear All,

    I am using sand hypoplastic model in my research and I have encountered some problem when looking into cyclic simple shear test in the range of small strains.

    Firstly, I have tried to simulate cyclic simple shear test from Shahnazari & Towhata (2002), Fig. 5, on Toyoura Sand. It is in the range of medium strains, up to 3%, starting from medium dense state of Dr=58%, finishing in dense state Dr=84%. The simulation looks really good (unfortunately I can not attach in the comment section the pdf I have prepared to visualize the problem more explicitly). The sample contracts systematically with cycles thus the stiffness increases as per the experiment.

    Secondly, I have subjected the same sample to cyclic loading but with significantly reduced strain amplitude, i.e. 0.1%. As expected, also here the sample contracts, however, the stiffness decreases with cycles which to me does not seem physical.

    The model is calibrated as shown in Herle & Gudehus (1999) Table VII for Toyoura Sand. Intergranular strain parameters are set to also rather common values: R=0.0001, m_R=5.0, m_T=2.0, Beta=0.5, ksi=6.0. I have tried using both umats, from prof. Masin and prof. Fellin, both give the same answers. I have also tried to look how the change of the constitutive model by Wegener & Herle (2014) changes the response but did not observe an improvement regarding my problem.

    I am wondering where is it I can be wrong here. Maybe some of you encountered a similar problem. Theoretically, I think I should be able to model sand behaviour for both strain levels with a single set of calibrated parameters.

    Thank you all in advance for any comments and tips on how to approach my problem.

    Regards

Leave a reply

©2019 SoilModels

Log in with your credentials

Forgot your details?