Finite element or different method (FEM/FDM) based analysis is an effective way for geotechnical design and disaster protection. Our objectives are to develop advanced constitutive models (e.g. elastic viscoplastic model of clay, critical state based models of sand), to implement them into available FEM/FDM codes, to develop smoothed particle finite element method (PFEM) with model implementation for large strain analysis while keeping the accuracy of small strain analysis, and to develop macroelement model inspired from constitutive modelling and beyond FEM/FDM analysis.

Topic 1: Constitutive Modelling

Related PhD Students | Peng-Lin LI

1.1 Time-dependency of soft soils - ANICREEP

Natural soft clays exhibit several features: (a) significant anisotropy developed during their deposition, sedimentation, consolidation history and any subsequent straining; (b) some apparent bonding which will be progressively lost during straining; and (c) time-dependent stress-strain behaviour which has a significant influence on the shear strength and the pre-consolidation pressure. Since all these features cannot be neglected, in the modelling we considered all above features. The application of the proposed model ANICREEP requires the same experimental information as needed for the Modified Cam Clay model, which makes the model attractive for geotechnical practice.

  • Li J, Yin Z-Y (2021). Time integration algorithms for elasto-viscoplastic models with multiple hardening laws for geomaterials: enhancement and comparative study. Arch. Comput. Methods Eng., 28: 3869–3886.
  • Li J, Yin Z-Y (2020). A modified cutting-plane time integration scheme with adaptive substepping for elasto-viscoplastic models. Int. J. Numer. Meth. Eng., 121(17): 3955-3978.
  • Jin YF, Yin Z-Y, Zhou WH, Yin JH, Shao JF (2019). A single-objective EPR based model for creep index of soft clays considering L2 regularization. Eng. Geol., 248(8): 242-255.
  • Yin Z-Y, Zhu QY, Yin JH, Ni Q (2014). Stress relaxation coefficient and formulation for soft soils. Géotech. Lett., 4(1): 45-51.
  • Yin Z-Y, Karstunen M, Chang CS, Koskinen M, Lojander M (2011). Modeling time-dependent behavior of soft sensitive clay. J. Geotech. Geoenviron. Eng. ASCE, 137(11): 1103-1113.
  • Yin Z-Y, Chang CS, Karstunen M, Hicher PY (2010). An anisotropic elastic viscoplastic model for soft clays. Int. J. Solids Struct., 47(5): 665-677.

1.2 Grading-dependency of granular soils - SIMSAND

Mechanical properties/behaviours are significantly affected by the grain size distribution of the granular soil, which is called “grading-dependency”. The grading change can be induced by grain breakage. Bigger sized grains are easier to be crushed. If the soil is gap-graded, the change of fines content can be induced by seepage force so-called suffusion/internal erosion. Currently, we focuses on how the soil grading evolves, what is mechanical consequence, and how to model the full coupling for engineering design.

  • Yin Z-Y (2021). Constitutive Theory of Granular Soils and Application. China Architecture Press, Beijing.
  • Yin Z-Y, Hicher P-Y, Jin YF (2020). Practice of constitutive modelling for saturated soils. Springer, Singapore.
  • Yin Z-Y, Hicher PY, Dano C, Jin YF (2017). Modeling the mechanical behavior of very coarse granular materials. J. Eng. Mech. ASCE, 143(1): C401600.
  • Yin Z-Y, Huang HW, Hicher PY (2016). Elastoplastic modeling of sand-silt mixtures. Soils Found., 56(3): 520–532.
  • Hu W, Yin Z-Y, Dano C, Hicher PY (2011). A constitutive model for granular materials considering grain breakage. Sci. China Technol. Sc., 54(8): 2188-2196.


Topic 2: User development via commercial codes

Related PhD Students | Jing-Cheng TENGMin-Hao ZHANGRui LIANG

The implementation of the advanced constitutive models into FEM/FDM codes is necessary for engineering design. We adopted some famous commercial codes for our model implementation: ABAQUS, PLAXIS and FLAC.

2.1 User-defined material – UMAT/VUMAT in ABAQUS

UMAT and VUMAT allow us to implement advanced constitutive models of soils. The former is typically for implicit calculation and small strain analysis, and the latter is typically for explicit calculation and large deformation analysis.

  • Jin Z, Yin Z-Y, Kotronis P, Li Z, (2019). Advanced numerical modelling of caisson foundations in sand to investigate the failure envelope in the H-M-V space. Ocean Eng., 190: 106394.
  • Yin Z-Y, Jin Z, Kotronis P, Wu ZX (2018). A novel SPH-SIMSAND based approach for modelling of granular collapse. Int. J. Geomech. ASCE, 18(11): 04018156.
  • Jin Y-F, Yin Z-Y, Wu Z-X, Daouadji A (2018), Numerical modeling of pile penetration in silica sands considering the effect of grain breakage, Finite Elem. Anal. Des., 144: 15–29.
  • Jin Y-F, Yin Z-Y, Wu Z-X, Zhou W-H (2018), Identifying parameters of easily crushable sand and application to offshore pile driving, Ocean Eng., 154, 416-429.

2.2 User-defined friction – FRIC/VFRIC in ABAQUS

FRIC and VFRIC allow us to implement advanced interface models of soil-structure. The former is for implicit calculation and the latter for explicit calculation. We implemented the recently developed exponential function based nonlinear incremental interface model.

  • Yang J, Yin Z-Y (2021). Soil-structure interface modelling with the nonlinear incremental approach. Int. J. Numer. Anal. Methods Geomech., 45(10): 1381-1404.

2.3 User-defined element – UEL/VUEL in ABAQUS

UEL and VUEL allow us to develop advanced multiphysics modelling. The former is for implicit calculation and small strain analysis, and the latter is for explicit calculation and large deformation analysis.

  • Yang J, Yin Z-Y, Laouafa F, Hicher P-Y (2020). Three-dimensional hydro-mechanical modelling of internal erosion in dike-on-foundation. Int. J. Numer. Anal. Methods Geomech., 44(8): 1200-1218.
  • Yang J, Yin Z-Y, Laouafa F, Hicher P-Y(2019). Internal erosion in dike-on-foundation modeled by a coupled hydro-mechanical approach. Int. J. Numer. Anal. Methods Geomech., 43(3): 663-683.

2.4 Practice of cohesive interface element

Cohesive interface elements are useful in modelling adhesives, bonded interfaces, gaskets, and rock fracture. The constitutive response of these elements depends on the specific application and is based on certain assumptions about the deformation and stress states that are appropriate for each application area.

  • Lin Y, Yin Z-Y, Wang X, Huang L (2021). A systematic 3D simulation method for geomaterials with block inclusions from image recognition to fracturing modelling. Theor. Appl. Fract. Mech., 117: 103194.

2.5 User-defined material – UDM in PLAXIS

UDM allows us to implement advanced models of soils in the code. Such models must be programmed in FORTRAN, then compiled as a Dynamic Link Library (DLL) and then added to the PLAXIS program directory. We implemented the ANICREEP model for geotechnical analysis relating to soft soils.

  • Yin Z-Y, Xu Q, Yu C (2015). Elastic viscoplastic modeling for natural soft clays considering nonlinear creep. Int. J. Geomech. ASCE, 15(5): A6014001.
  • Karstunen M, Yin Z-Y*(2010). Modelling time-dependent behaviour of Murro test embankment. Géotechnique, 60(10): 735-749.

2.6 User-defined material – UDM in FLAC

UDM allows us to implement advanced models of soils in the code, similar to that in PLAXIS. We implemented some advanced soil models for geotechnical analysis.

  • Yang J, Yin Z-Y, Liu XF, Gao FP (2020). Numerical analysis for the role of soil properties to the load transfer in clay foundation due to the traffic load of the metro tunnel. Transp. Geotech., 23: 100336.


Topic 3: Development of smoothed PFEM

Related PhD Students | Lu-Jia YUZe-Yu WANGXian-Han WU

Geotechnical structures involve small deformation for the design purpose to large deformation for the failure analysis and disaster protection. Particle finite element method (PFEM) has both the accuracy of small deformation and the ability of large deformation, due to which we adopted the framework of PFEM to enhance/develop more advanced methods.

3.1 Edge-based smoothed PFEM

We developed a novel edge-based smoothed PFEM for large deformation analysis.

  • Jin Y-F, Yuan W-H, Yin Z-Y, Cheng Y-M. An edge-based strain smoothing particle finite element method for large deformation problems in geotechnical engineering[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2020, 44(7): 923-941.
  • Jin Y-F, Yin Z-Y, Yuan W-H. Simulating retrogressive slope failure using two different smoothed particle finite element methods: A comparative study[J]. Engineering Geology, 2020, 279: 105870.

3.2 Implicit edge-based smoothed hydromechanical PFEM

Based on the proposed edge-based particle finite element method (ES-PFEM), we developed the hydromechanical coupling of ES-PFEM (C-ES-PFEM) with implementing ANICREEP model.

  • Jin, Y.-F., Yin, Z.-Y., Li, J., Dai, J.-G., 2021. A novel implicit coupled hydro-mechanical SPFEM approach for modelling of delayed failure of cut slope in soft sensitive clay. Computers and Geotechnics 140, 104474.

3.3 Explicit stable node-based smoothed PFEM (SNS-PFEM)

To solve the drawbacks (overly soft and temporal instability) of the node-based particle finite element method (NS-PFEM), we developed stable node-based NS-PFEM (SNS-PFEM) and applied it to large deformation analysis.

  • Jin, Y.-F., Yin, Z.-Y., Zhou, X.-W., Liu, F.-T., 2021. A stable node-based smoothed PFEM for solving geotechnical large deformation 2D problems. Computer Methods in Applied Mechanics and Engineering 387, 114179.


Topic 4: Macroelement model

Related PhD Students | Min-Hao ZHANG

Soil–structure interaction (SSI) consists of the interaction between soil (ground) and a structure built upon it, in which the foundation structures with their surrounding soils (in certain range which soil is disturbed) can be regarded as an entire system, so-called a macro-element, with global forces (or moments)-displacements (or rotations) responses. Currently, we focused on the design of caisson foundation by means of discrete element method, finite element method and mesh-free method for progressive failure analysis and failure envelope investigation, which have been later applied to establish “forces-displacements” models in structural level so-called macro-element models.

  • Yin Z-Y, Teng JC, Li Z, Zheng YY (2020). Modelling of suction bucket foundation in clay: from finite element analyses to macro-elements, Ocean Eng., 210: 107577.
  • Jin Z, Yin Z-Y, Kotronis P, Li Z, Tamagnini C (2019). A hypoplastic macroelement model for a caisson foundation in sand under monotonic and cyclic loadings. Marine Structures, 66: 16-26.


Topic 5: Ocean modelling

Related PhD Students | Chang HE

The Pearl River Estuary and Hong Kong waters (PRE-HK) is one of the most energetic coastal areas in view of oceanic circulation. Tides from the South China Sea brings numerous energy and momentum which were dissipated around the PRE-HK when interacting with river plumes and complex coastlines. A high-resolution model (50m – 10km) was well-validated, based on the Finite Volume Community Ocean Model. Currently, we focused on the flow structure and the role of monsoon wind and tides, as well as macro-vortices generation and transport around the PRE-HK.

  • He, C., Yin, Z.-Y., Stocchino, A., Wai, O.W.H., Li, S., 2022. The coastal macro-vortices dynamics in Hong Kong waters and its impact on water quality. Ocean Modelling 175, 102034.