Open call: PhD position in geomechanics 2014-2018

suction

deformation

volumetric strain

shear strain

• Title of the PhD project: Finite element implementation and application of a hypoplastic model for unsaturated expansive clays.
  
  
• Research group: Soil Mechanics (at the Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Charles University in Prague).
  
  
• Project supervisor: Doc. RNDr. David Mašín, M.Phil., Ph.D.
  
  
• STARS programme description: www.stars-natur.cz
  
  
• Project description: Recently, Wong and Mašín developed a coupled hydro-mechanical hypoplastic model for partially saturated soils incorporating very small strain stiffness. Hysteretic void ratio dependent water retention model has been incorporated into the existing hypoplastic model. This required thorough revision of the model structure to allow for the hydro-mechanical coupling dependencies. Subsequently, the small strain stiffness effects were incorporated using the intergranular strain concept modified for unsaturated conditions. New features included suction-dependent size of the elastic range and an updated evolution equation for the intergranular strain. The model is suitable for capturing cyclic loading phenomena, induced for example by environmental effects during wetting and drying cycles. Purpose of this research project is to implement the model into a coupled hydro-mechanical finite element code for unsaturated soils (CodeBright, SIFEL). General implementation in the form of user-defined subroutine will first be programmed. Subsequently, the implementation will be linked to the coupled finite element code using interface implementation. Once the model is implemented, it will be evaluated with respect to various boundary value problems. If some model deficiencies are discovered based on the evaluation, the model will be further developed.
  
  
• Important dates:
  • 1. 2. 2014: Application web interface open at www.stars-natur.cz/application
  • 28. 2. 2014: Deadline for application
  • 1. 3. - 31. 3. 2014: Interviews with shortlisted candidates (Skype interviews accepted with foreign candidates)
  • 1. 4. 2014: Successful candidate announced
  • 1. 10. 2014 - 30. 9. 2018: PhD project
  
  
• Eligible candidates: The position is open to all applicants who hold a master's degree or equivalent in geotechnical engineering, geomechanics, geophysics or other related field of studies. The candidate should be skilled in programming and should have a good insight into applied mathematics. The position is also open to students who are in the last year of their studies and will be able to present their degree diploma at the beginning of their PhD study. The candidate should be proficient in English; however, no formal English exam (such as TOEFL) is required. There is no restriction on the nationality of candidates.
  
  
• Scholarship: PhD student will receive a state-guaranteed scholarship of 6050 Czech crowns per month in the first year of study; the scholarship increases slightly over the course of 4 years for which it is granted. In addition to the state scholarship, the STARS program students will are also granted the STARS-scholarship of 10 000 CZK per month. Their net income will therefore be at least 16 050 CZK per month (~650 Euro). The remuneration may be further augmented by the project supervisor.
  
  
• How to apply: Applications will only be accepted using web interface at www.stars-natur.cz/application (opens 1. 2. 2014 at the latest).
  
  
• Study, research and living in Prague, Czech Republic: PDF info brochure by http://www.euraxess.cz.
  
  
• Relevant publications of the research group:
  1. Mašín, D. (2013). Clay hypoplasticity model including stiffness anisotropy. Géotechnique (in print).
  2. Wong, K. S., Mašín, D. and Ng, C. W. W. (2014). Modelling of shear stiffness of unsaturated fine grained soils at very small strains. Computers and Geotechnics 56, 28-39. [Preprint PDF]
  3. Mašín, D. and Rott, J. (2013). Small strain stiffness anisotropy of natural sedimentary clays: review and a model. Acta Geotechnica (in print). [Preprint PDF]
  4. Mašín, D. (2013). Double structure hydromechanical coupling formalism and a model for unsaturated expansive clays. Engineering Geology 165, 73-88. [Preprint PDF]
  5. Ng, C. W. W., Boonyarak, T. and Mašín, D. (2013). Three-dimensional centrifuge and numerical modeling of the interaction between perpendicularly crossing tunnels. Canadian Geotechnical Journal 50, No. 9, 935-946. [Preprint PDF]
  6. Blecha, V. and Mašín, D. (2013). Observed and calculated gravity anomalies above a tunnel driven in clays - implication for errors in gravity interpretation. Near Surface Geophysics 11, No. 5, 569-578. [Preprint PDF]
  7. Mašín, D. (2013). Clay hypoplasticity with explicitly defined asymptotic states. Acta Geotechnica 8, No. 5, 481-496. [Preprint PDF]
  8. Mašín, D. (2012). Asymptotic behaviour of granular materials. Granular Matter 14, No. 6, 759-774. [Preprint PDF]
  9. Trhlíková, J., Mašín, D. and Boháč, J. (2012). Small strain behaviour of cemented soils. Géotechnique 62, No. 10, 943-947. [Preprint PDF]
  10. Mašín, D. and Khalili, N. (2012). A thermo-mechanical model for variably saturated soils based on hypoplasticity. International Journal for Numerical and Analytical Methods in Geomechanics 36, No. 12, 1461-1485. [Preprint PDF]
  11. Mašín, D. (2012). Hypoplastic Cam-clay model. Géotechnique 62, No. 6, 549-553. [Preprint PDF]
  12. Najser, J., Mašín, D. and Boháč, J. (2012). Numerical modelling of lumpy clay landfill. International Journal for Numerical and Analytical Methods in Geomechanics 36, No. 1, 17-35. [Preprint PDF]
  13. D'Onza, F., Gallipoli, D., Wheeler, S., Casini, F., Vaunat, J., Khalili, N., Laloui, L., Mancuso, C., Mašín, D., Nuth, M., Pereira, J. M. and Vassallo, R. (2011). Benchmark of constitutive models for unsaturated soils. Géotechnique 61, No. 4, 283-302.
  14. Svoboda, T. and Mašín, D. (2011). Comparison of displacement fields predicted by 2D and 3D finite element modelling of shallow NATM tunnels in clays. Geotechnik 34, No. 2, 115-126. [Preprint PDF]
  15. Suchomel, R. and Mašín, D. (2011). Probabilistic analyses of a strip footing on horizontally stratified sandy deposit using advanced constitutive model. Computers and Geotechnics 38, No. 3, 363-374. [Preprint PDF]
  16. Svoboda, T., Mašín, D. and Boháč, J. (2010). Class A predictions of a NATM tunnel in stiff clay. Computers and Geotechnics 37, No. 6, 817-825. [Preprint PDF]
  17. Suchomel, R. and Mašín, D. (2010). Comparison of different probabilistic methods for predicting stability of a slope in spatially variable c-phi soil. Computers and Geotechnics 37, No. 1-2, 132-140. [Preprint PDF]
  18. Mašín, D. (2010). Predicting the dependency of a degree of saturation on void ratio and suction using effective stress principle for unsaturated soils. International Journal for Numerical and Analytical Methods in Geomechanics 34, No. 1, 73-90. [Preprint PDF]
  19. Mašín, D. (2009). Comparison of predictive capabilities of selected elasto-plastic and hypoplastic models for structured clays. Soils and Foundations 49, No. 3, 381-390. [Preprint PDF]
  20. Mašín, D. (2009). 3D modelling of a NATM tunnel in high K₀ clay using two different constitutive models. ASCE Journal of Geotechnical and Geoenvironmental Engineering 135, No. 9, 1326-1335. [Preprint PDF]
  21. Hájek, V., Mašín, D. and Boháč, J. (2009). Capability of constitutive models to simulate soils with different OCR using a single set of parameters. Computers and Geotechnics 36, No. 4, 655-664. [Preprint PDF]
  22. Gudehus, G. and Mašín, D. (2009). Graphical representation of constitutive equations. Géotechnique 59, No. 2, 147-151. [Preprint PDF]
  23. Mašín, D. and Khalili, N. (2008). A hypoplastic model for mechanical response of unsaturated soils. International Journal for Numerical and Analytical Methods in Geomechanics 32, No. 15, 1903-1926. [Preprint PDF]
  24. Mašín, D. and Herle, I. (2007). Improvement of a hypoplastic model to predict clay behaviour under undrained conditions. Acta Geotechnica 2, No. 4, 261-268. [Preprint PDF]
  25. Mašín, D. (2007). A hypoplastic constitutive model for clays with meta-stable structure. Canadian Geotechnical Journal 44, No. 3, 363-375. [Preprint PDF]
  26. Stallebrass, S. E., Atkinson, J. H. and Mašín, D. (2007). Manufacture of Samples of Overconsolidated Clay by Laboratory Sedimentation. Géotechnique 57, No. 2, 249-253.
  27. Mašín, D., Tamagnini, C., Viggiani, G. and Costanzo, D. (2006). Directional response of a reconstituted fine-grained soil - Part II: performance of different constitutive models. International Journal for Numerical and Analytical Methods in Geomechanics 30, No. 13, 1303-1336. [Preprint PDF]
  28. Mašín, D. and Herle, I. (2005). State boundary surface of a hypoplastic model for clays. Computers and Geotechnics 32, No. 6, 400-410. [Preprint PDF]
  29. Mašín, D. (2005). A hypoplastic constitutive model for clays. International Journal for Numerical and Analytical Methods in Geomechanics 29, No. 4, 311-336. [Preprint PDF]