Alexander Rohe, Dongfang Liang

1. Deltares, Delft, The Netherlands, E-mail: alex.rohe@deltares.nl

2. Department of Engineering, University of Cambridge, Cambridge, UK

Modelling large deformation and soil–water–structure interaction with material point method: Briefing on MPM2017 conference*

Alexander Rohe1, Dongfang Liang2

1. Deltares, Delft, The Netherlands, E-mail: alex.rohe@deltares.nl

2. Department of Engineering, University of Cambridge, Cambridge, UK

2017,29(3):393-396

The 1st International Conference on the Material Point Method for “Modelling Large Deformation and Soil–Water–Structure Interaction” (MPM2017) was held in Delft, The Netherlands on 10-13 January 2017. This is the first conference organised by the Anura3D MPM Research Community, following a series of international workshops and symposia previously held in The Netherlands, UK, Spain and Italy, as part of the European Commission FP7 Marie-Curie project MPM-DREDGE. We are delighted to present seven contributions in this Special Column of the Journal of Hydrodynamics, and take this opportunity to announce that the 2nd conference, MPM2019, will be held in Cambridge, UK in January 2019.

Material point method, soil–water–structure interaction, meshfree methods, particle methods

Introduction

The soil–water interaction and large deformation of fluid-saturated soils are of great interest in many environmental and civil engineering areas, such as geophysics, engineering applications and industrial processes. In particular, sudden catastrophic landslides, flowslides, avalanches, and debris flows cause much damages in many parts of the world due to their rapid movement and large travel distances. Similarly, failures of man-made structures (i.e., levees, dykes, and embankments) that can occur during intense rainfall, storm surges or tsunamis can also result in severe damages.

In problems of this type, it is important to predict the subsequent deformations and travel distances, after having identified the failure mechanism. Generally, it is difficult to use classical mesh-based methods, such as the finite difference method (FDM) and finite element method (FEM), to model the behaviour that involves large deformations due to the severe mesh distortion and the associated errors. Most of the continuum techniques that have been used to model large soil deformations treat the soil as a visco-plastic fluid(i.e., Bingham fluid) and fluid-mechanics-based equations have been used. However, it may be difficult to determine these hydrodynamic parameters.

The recent advances in particle methods, or meshfree methods, that can be derived in the continuum mechanics framework allow the modelling of large deformation behaviour of both fluids and solids while using conventional constitutive models. A wide range of meshfree methods is available in literature and these include smoothed particle hydrodynamics (SPH) method, moving particle semi-implicit method, material point method (MPM), finite point method, element free Galerkin method and particle-in-cell method. Many of these meshfree methods have been mainly applied separately to either solid mechanics or fluid dynamics problems. Only recently have they been applied to study coupled solid and fluid mechanics problems, with SPH and MPM models having gain some popularity.

Our studies are focused on MPM, in which Lagrangian point masses, or material points, move through an Eulerian background mesh with an arbitrary shape and topology. Although there is a mesh, it is only used to solve governing equations and chosen purely for computational convenience within a single time step. All properties of the continuum are assigned to the material points, and all information is carried bythese material points while the mesh does not carry any permanent information. The major advantage of this method, compared to other particle methods, is that application of boundary conditions is straightforward, since they can be directly applied to the nodes of the background grid as in the FEM. The interpenetration of material points is avoided since the material points move in a single valued velocity field (i.e., material point velocities are interpolated from the nodal velocities). The use of Lagrangian material points conserves mass and allows the history-dependent material models to be deployed. Moreover, the discrete equations for the momentum balances are obtained on the background grid similar to the finite element method with an updated Lagrangian formulation. As such, the MPM has many similarities to the FEM, and therefore has the advantage of using advanced features that are well established in the FEM.

1. Anura3D MPM Research Community

The MPM 2017 Conference was organised by the Anura3D MPM Research Community (www.anura3d.com). This international collaboration brings together complementary expertise of seven groups carrying out research on numerical modelling of large deformations and soil–water–structure interactions. At the moment, the Anura3D MPM Research Community is a collaboration of the following partners:

(1) Soil and Rock Mechanics Research Group, Civil Engineering School, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain, represented by Prof. Eduardo Alonso.

(2) GeoSystems (Geoengineering) Group, Civil and Environmental Engineering Department, University of California Berkeley, United States, represented by Prof. Kenichi Soga.

(3) Geotechnical and Environmental Research Group, Engineering Department, University of Cambridge, United Kingdom, represented by Dr. Dongfang Liang.

(4) Faculty of Civil Engineering and Geosciences, Delft University of Technology, The Netherlands, represented by Prof. Wim Uijttewaal.

(5) Unit Geo-engineering Deltares, Delft, The Netherlands, represented by Mr. Ipo Ritsema.

(6) Institute of Geotechnical Engineering and Construction Management, Technische Universität Hamburg-Harburg (TUHH), Germany, represented by Prof. Jürgen Grabe.

(7) Research Group Geotechnics, Department of Civil, Environmental and Architectural Engineering, Università degli Studi di Padova, Italy, represented by Prof. Paolo Simonini.

The Research Community has developed and maintained its own MPM computational platform– Anura3D. The current version of the software adopts a dynamic MPM formulation, and is able to simulate single-phase and multiphase materials. A fully-coupled hydro-mechanical approach has been implemented to model the saturated porous media, coupling the mechanical behaviour of solid skeleton, pore fluid and free surface water in a unified framework. Other features of Anura3D include the contact algorithms and an extensive library of material constitutive laws. Apart from the frequent workshops held sequentially in the member institutions of the Community, we have also organised two MPM Training Courses: the first one in Cambridge (UK) on 3 May 2016 and the second one in Delft (The Netherlands) on 13 January 2017. These training courses focus on presenting the latest MPM formulations capable of simulating the strong coupling between soil and water phases, and provide opportunities for the attendees to gain firsthand experience of the Anura3D software through a set of practical exercises. The next training course will be held on 29 September 2017 in Hamburg (Germany), for which further information can be found on the website of the Research Community (www.anura3d.com).

2. MPM2017 conference summary

The 1st International Conference on the Material Point Method (MPM2017) for “Modelling Large Deformation and Soil–Water–Structure Interaction” was held in Delft (The Netherlands) on 10-13 January 2017. This was the first conference following a series of international workshops and symposia previously held in Padova (2016), Barcelona (2015), Cambridge (2014) and Delft (2013) within the European Community’s project MPM-DREDGE.

MPM-DREDGE is an Industry–Academia Partnerships and Pathways (IAPP) project funded from the Seventh Framework Programme (FP7/2007-2013) of the European Commission under the grant agreement PIAP–GA–2012–324522during 2013-2017. The MPM-DREDGE project deals with the numerical simulation of large deformations and the modelling of soil–water interactions. The project forms a consortium that connects two full participants (University of Cambridge and Deltares) with four supporting partners from the European dredging industry, which engages key private stakeholders in the dredging sector. The researchers and leading scientists include: Dr. Dongfang Liang, Prof. Kenichi Soga, Dr. James Fern, Dr. Alba Yerro, Mr. Xuanyu Zhao (all based in Cambridge) and Dr. Hans Teunissen, Dr. Bruno Zuada Coelho, Dr. Mario Martinelli, Dr. Alexander Rohe, Mr. Joost Breedeveld (all based in Deltares).

The overarching aim of the MPM-DREDGE project is to provide high-quality training to a group of young researchers, contributing to the development of a new generation of multidisciplinary researchers ableto work in the challenging field of advanced computational modelling of large deformations and soil-water interactions. The goal is to develop, validate and demonstrate a numerical tool for the modelling and simulation of dredging applications, which resulted in the Anura3D implementation of the material point method. The main focus is on the modelling of soil–fluid interaction problems related to the following three dredging applications:

(1) Dropping of geocontainers with interaction between pore water and open water.

(2) Liquefaction and marine slope slides including the dredging of soils.

(3) Erosion and scour around offshore and nearshore structures.

The aim of the MPM2017 conference was to provide an international forum for presenting and discussing the latest developments in both the fundamentals and applications of state-of-the-art computational methods that can be effectively used for solving a variety of large deformation problems in geotechnical and hydraulic engineering. Special focus is on the numerical modelling of the interaction between soils, water and structures where the interface and state transition between solid and fluid behaviour play an essential role.

The peer reviewed papers contained in the conference proceedings have been authored by academics, researchers and practitioners from many countries worldwide. The papers cover numerous important aspects related to the numerical modelling of large deformations and soil–water–structure interactions, ranging from the recent mathematical developments of the material point method, across benchmark examples, up to practical engineering applications.

In total, 110 delegates from 20 countries attended the conference; 45 papers were finally included in the conference proceedings. The keynote speakers are: Prof. Pieter A. Vermeer (Deltares, The Netherlands), Prof. Pedro Arduino (University of Washington Seattle, USA), Prof. Xiong Zhang (Tsinghua University Beijing, China), Prof. Deborah Sulsky (University of New Mexico Albuquerque, USA), Prof. Kenichi Soga (University of California Berkeley, USA) and Prof. Zdzisław Więckowski (Technical University of Łódź, Poland).

A selection of most relevant papers[1-7]is included as featured articles in this Special Column of the Journal of Hydrodynamics. The first three papers report the theoretical development and application in various hydrodynamic areas, with the first paper[1]involving dam-break floods, the second paper[2]proposing a fully-incompressible MPM formulation and the third paper[3]examining the coastal wave dynamics with a hybrid particle-mesh method. They are followed two investigations of the dynamic water-solid coupling problems using the double-point MPM. The fourth paper[4]investigates the strong interaction between the movement of a poroelastic solid body and the surrounding fluid, and the fifth paper[5]simulates the soil fluidisation phenomenon under the action of strong upward seepage flows. Last but not the least, there are two papers on flow-like landslides, with one on submarine landslide runout[6]and the other on the initiation and development of aerial landslides[7]. The full conference proceedings are available through the conference website www.mpm2017.eu or in the Procedia Engineering (2017), Volume 175, Pages 1-372.

3. Continuing collaboration with Journal of Hydrodynamics

We highly appreciate that the Journal of Hydrodynamics agrees to publish seven of our conference papers after substantial expansion and revision. Because of its close connection to the FEM, the MPM has mainly been applied in solid mechanics and geotechnics. Whereas, its application in fluid mechanics and hydraulics has been limited. These papers address various hydrodynamic and soil–fluid interaction problems. We hope that these papers will help raise awareness of MPM in the hydrodynamic research community and promote cross-disciplinary studies.

As its name suggests, the Journal of Hydrodynamics reflects a broad range of research activities in the field of hydrodynamics. The Journal offers a platform for exchanging ideas and experiences, and promoting the cutting-edge development of hydrodynamic research and its applications. We share the view with the journal that multidisciplinary research breeds innovation and advancement of traditional research subjects, and we attach great importance to our collaboration with this distinguished Journal. We are proud that, among the 7 Board Members of the Anura3D MPM Research Community, Prof. Soga from UC Berkeley and Dr. Liang from University of Cambridge both serve on the Editorial Board of the Journal of Hydrodynamics. We will regularly recommend outstanding papers written by the members of the Anura3D MPM Research Community to the Journal. We are also pleased to name the Journal of Hydrodynamics as a supporter of the MPM2019 conference, which will be held in the University of Cambridge in January 2019.

Acknowledgements

We are grateful to the support provided by the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement No. PIAG-GA-2012-324522 “MPM-DREDGE”.

[1] Zhao X., Liang D., Martinelli M. Numerical simulations of dam-break floods with MPM [C]. Procedia Engineering. 2017, 175: 133-140.

[2] Kularathna S., Soga K. Projection method in material point method for modeling incompressible materials [C]. Procedia Engineering. 2017, 175: 57-64.

[3] Maljaars J., Labeur R. J., Möller M. et al. A numerical wave tank using a hybrid particle-mesh approach [C]. Procedia Engineering. 2017, 175: 21-28.

[4] Zuada Coelho B., Rohe A., Soga K. Poroelastic solid flow with material point method [C]. Procedia Engineering. 2017, 175: 316-323.

[5] Bolognin M., Martinelli M., Bakker K. J. et al. Validation of material point method for soil fluidisation analysis [C]. Procedia Engineering. 2017, 175: 233-241.

[6] Dong Y., Wang D., Randolph M. F. Runout of submarine landslide simulated with material point method [C]. Procedia Engineering. 2017, 175: 357-364.

[7] Vardon P. J., Wang B., Hicks M. A. Slope failure simulations with MPM [C]. Procedia Engineering. 2017, 175: 258-264.

10.1016/S1001-6058(16)60748-5

February 12, 2017, Revised March 22, 2017)

*Biography:Alexander Rohe, Male, Ph. D., Senior Engineer