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8th european conference on numerical methods in geotechnical engineering (NUMGE)

作者： Lanzano, G. de Magistris, F. Santucci Bilotta, E. Univ Molise DiBiT Dept Termoli CB Italy Univ Napoli Federico II DICEA Dept Naples Italy

ISBN: (纸本)9781315751825;9781138026872

numerical analyses could represent a very useful tool to model the seismic behavior of infrastructures. Sometimes this is a preferable way to study problems of seismic soil/structure interaction, because true scale monitoring and physical modeling could be not convenient. For the purpose of dynamic analyses, recent release of PLAXIS 2D implements the Hardening Soil Small Strain model (HSSS), which is a modification of the isotropic hardening model (HS), including the shear strain dependence of soil stiffness modulus and damping ratio. Moreover, the non-linear stress-strain relation of HS model is used to represent both transient and permanent behavior of the soil under cyclic dynamic actions. In this paper, the HSSS material model was used to reproduce the behavior of shallow tunnels under dynamic loadings. the input mechanical parameters for a Leighton Buzzard sand (fraction E) were calibrated on the basis of advanced laboratory tests and experimental evidence of dynamic centrifuge models. the results were finally compared to the physical modeling findings.

关键词： Soils

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Modeling the positioning of single needle electrodes for the treatment of breast cancer in a clinical case

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BIOMEDICAL engineering ONLINE 2015年第3-Sup期14卷 S1-S1页

作者： Denzi, Agnese Strigari, Lidia Di Filippo, Franco Botti, Claudio Di Filippo, Simona Perracchio, Letizia Ronchetti, Mattia Cadossi, Ruggero Liberti, Micaela Univ Roma La Sapienza Dept Informat Engn Elect & Telecommun DIET Italian Interuniv Ctr Elect Fields & Biosyst ICEm I-00184 Rome Italy Regina Elena Inst Canc Res Lab Med Phys & Expert Syst I-00144 Rome Italy Regina Elena Inst Canc Res Dept Surg I-00144 Rome Italy Regina Elena Inst Canc Res Dept Pathol I-00144 Rome Italy IGEA SpA Clin Res Carpi Italy

Background: Breast cancer is the most common cancer in women worldwide and is the second most common cause of cancer death in women. Electrochemotherapy (ECT) used in early-phase clinical trials for the treatment of primary breast cancer resulted in a not complete tumor necrosis in most cases. the present study was undertaken to analyze the feasibility to use ECT to treat patients with histologically proven unifocal ductal breast cancer. In particular, results of ECT treatment in a clinical case are compared with the ones of a simplified 3D dosimetric model. methods: this clinical study was conducted with the pulse generator Cliniporator Vitae (IGEA, Carpi, Italy). ECT procedures were performed according to ESOPE standard operating procedures. Five single needle electrodes were used with one positioned in the center of the tumor, and the other four distributed around the nodule. Histological images of the resected tumor are compared with the maps of the electric field obtained with a simplified 3D model in Comsol Multiphysics v 4.3. Results: the results of the clinical case demonstrated a reduced efficacy of the ECT treatment described. the proposed simple numerical model of the breast tumor located in a low conductive tissue suggests that this is due to the reduced electric field induced inside the tumor with such 5 electrodes placement. However, where the electric field is predicted higher than the reversible electroporation threshold (E>400 V/cm), also the histological images confirm the necrosis of the target with a good agreement between the modeled and clinical results. Conclusions: the results suggest the dependence of the effectiveness of the treatment on the careful placement of the electrodes. A detailed planned procedure for the tumor analysis after the treatment is also needed in order to better correlate the single electrode positions and the histological images. Simulation models could be used to identify better electrodes configuration in planning the

关键词： Electrochemotherapy Breast Cancer Single Needle Electrodes numerical Modeling Electrodes Positioning

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Assessing the effects of constructing the Colosseo/Fori Imperiali station on the Basilica di Massenzio in Rome, Italy

Assessing the effects of constructing the Colosseo/Fori Impe...

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8th european conference on numerical methods in geotechnical engineering, NUMGE 2014

作者： Schroeder, F.C. Merritt, A.S. Menkiti, C.O. Caianiello, M. Potts, D.M. Sorge, R. Geotechnical Consulting Group LLP London United Kingdom Studio Geotecnico Italiano Milan Italy Imperial College London United Kingdom Metro C S.c.p.A. Rome Italy

ISBN: (纸本)9781138026889

Colosseo/Fori Imperiali is a key station of the San Giovanni-Venezia stretch on the new Metro Line C in Rome, Italy. It provides interchange facilities to the existing Line B and direct access to some of Rome's most important monuments, including the Colosseum and the Basilica di Massenzio. the works are ongoing in 2014 and the station comprises excavations for the main station box, which is in excess of 30m deep, approximately 130m long and up to 42m wide, as well as for a sub-station and station entrances, which are around 8m depth. there is a minimum distance of approximately 10m between the station and the Basilica, which was the largest building of the Roman Forum but its remains are now in a cracked and vulnerable condition. Given the historic importance of the Basilica and the close proximity of the station, ground movements had to be predicted and their potential effects on the monument required careful consideration. this paper presents the 3D FE analysis that was undertaken to enable this assessment and determine requirements for additional mitigation measures. Some mitigation measures were already implemented, including alignment refinement to optimize the box configuration and to position it as far from the monument as practicable, the use of stiff retaining wall systems, sufficiently deep to cut-off groundwater flow, and emphasis on good construction control. the analysis results demonstrated that, despite the large depth and size of the excavation for the final station box configuration, the effects on the monument would be minimal and so active intervention at the Basilica could be limited to detailed monitoring, temporary support and some strengthening work. © 2014 Taylor & Francis Group, London.

关键词： Groundwater flow

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Coupled analysis of a strutted excavation in soft soil: Study of the effect of constructing a jet-grout base slab

Coupled analysis of a strutted excavation in soft soil: Stud...

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8th european conference on numerical methods in geotechnical engineering, NUMGE 2014

作者： Borges, J.L. Monteiro, A.S. Department of Civil Engineering Faculty of Engineering University of Porto Porto Portugal

ISBN: (纸本)9781138026889

Several solutions can be used in practice to minimize the wall and ground displacements and improve stability against bottom heave failure in strutted excavations in soft soils. One possible solution consists of extending the wall below the excavation base and, before excavation, constructing a jet grout slab to support the wall below the excavation base. In the present study, a strutted excavation in soft soil is analyzed, using a computer code based on the finite element method;the consolidation effect is *** solutions (casesA and B) of the same strutted excavation are analyzed;a jet-grout base slab is considered in case A while none jet-grout slab is modelled in case B. Another pertinent issue in excavations in soft soils is the excess pore pressure generation during excavation and its dissipation after that stage (consolidation). After construction, there are pore pressure gradients in the ground that determine a consolidation process. this process is dependent on both the magnitude of excess pore pressure at the end of excavation and the long term equilibrium conditions of water pore pressure. the computer code incorporates the Biot consolidation theory (coupled analysis) with soil constitutive relations simulated by the p-q-θ critical state model. Special emphasis is given to the analysis, during and after the construction period, of the pore pressures, shear stresses, stress levels and displacements in the ground, as well as strut compression loads, wall displacements and bending moments, earth pressures on the wall faces and compression loads and bending moments on the jet-grout slab. the results clearly show that the use of the jet-grout slab significantly reduces the wall and ground displacements and wall bending moments. Increases of the ground surface settlements on the unexcavated side in response to consolidation are also observed as excess pore pressure generated during excavation dissipates in time. © 2014 Taylor & Francis Group, London.

关键词： Finite element method

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numerical simulation of snow avalanches: Modelling dilatative processes with cohesion in rapid granular shear flows

Numerical simulation of snow avalanches: Modelling dilatativ...

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8th european conference on numerical methods in geotechnical engineering (NUMGE)

作者： Bartelt, P. Buser, O. Buehler, Y. Dreier, L. Christen, M. SLF WSL Inst Snow & Avalanche Res Davos Switzerland

ISBN: (纸本)9781315751825;9781138026872

numerical simulation tools are used in snow science to predict avalanche runout distances. the results are applied to plan and develop avalanche mitigation strategies to protect mountain communities. Fluid dynamics equations describing mass and momentum conservation of the flowing snow are the basic physical elements of the numerical models. Advanced models now include additional balance equations describing the production and decay of kinetic energy associated with random granule motion. Because the avalanche is running on a hard surface (the ground) and contains a free upper surface (the flow height), shearing at the base or within the flow necessarily implies the production of random fluctuation energy and the expansion of the flow volume. the expansion is often rapid, leading to explosive eruptions of ice-dust plumes at the avalanche front. In this presentation we present a numerical model of this process, explaining the mechanics of the volume expansion and the role of random fluctuation energy. the process is mediated by the granular properties of the snow clods, including granule size, temperature and moisture content. Of particular importance is the material cohesion. Cohesion not only modifies the constitutive relation for shearing, but also mediates the energy fluxes associated with the fluctuation energy. To demonstrate our modelling approach we present an example simulation of a real snow avalanch in general three-dimensional terrain.

关键词： numerical models

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numerical modeling of stone columns with installation effects

Numerical modeling of stone columns with installation effect...

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8th european conference on numerical methods in geotechnical engineering (NUMGE)

作者： Castro, J. Karstunen, M. Sivasithamparam, N. Univ Cantabria E-39005 Santander Spain Chalmers Univ Technol Gothenburg Sweden Norwegian Geotech Inst Oslo Norway

ISBN: (纸本)9781315751825;9781138026872

Stone column installation modifies the state of the surrounding soil, and therefore, influences the ground improvement achieved with the stone column treatment. the paper presents numerical simulations investigating the settlement reduction caused by stone columns in a natural soft clay, accounting for the modification of soil state caused by stone column installation. these installation effects have been previously studied by modelling the installation as an undrained expansion of a cylindrical cavity. A "unit cell", i.e. only one end-bearing stone column and its corresponding surrounding soil, is modelled in axial symmetry using the finite element code Plaxis. the properties of the soft clay correspond to Bothkennar clay, a soft (Carse) clay from Scotland (UK). the complexity of this material is simulated via an advanced constitutive formulation able to account for the soil anisotropy, namely S-CLAY1. the results show that the changes in the stress field, such as the increase of radial and mean stresses, and the loss of overconsolidation have a positive influence on the settlement reduction, excepting for low loads. Furthermore, column installation and subsequent loading cause several changes in the soil fabric. those changes have a positive effect in reducing the settlement because energy is dissipated in the evolution of anisotropy. Parametric studies of the influence of the coefficient of earth pressure at rest after column installation are also presented.

关键词： numerical models

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numerical simulation of pile installation processes in dry and saturated granular soils

Numerical simulation of pile installation processes in dry a...

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8th european conference on numerical methods in geotechnical engineering (NUMGE)

作者： Grabe, J. Pucker, T. Hamann, T. Hamburg Univ Technol Insitute Geotech Engn & Construct Management Hamburg Germany

ISBN: (纸本)9781315751825;9781138026872

the installation process of piles influences the surrounding soil and vice versa. thereby, the pile capacity depends on the installation process. In the past the installation processes of jacked, driven and vibratory driven piles in granular soils have been investigated numerically by several researchers. Nowadays, the use of modern numerical methods makes the simulation of pile drilling possible. Hence, numerical simulations of the drilling process are presented. the influence on the surrounding soil is investigated and compared to field measurements. the drilling parameters, such as penetration velocity and rotational speed are varied to study their effect on the installation process. Considering fully saturated soil, the mechanical behaviour of the soil is influenced by the excess pore pressures depending on the permeability of the soil. the numerical simulation of two phase materials, e.g. water and soil, in dynamic analyses is necessary to simulate pile installation processes in saturated soils considering partially drained conditions. the numerical modeling of fully saturated soil within dynamic analyses is still subject of research, e.g. Al-Kafaji (2013). Hence, a method is introduced to provide such calculations. Pile installation process simulations in saturated granular soils are presented and the influence of the water is investigated. the results are compared to pile installation simulations in dry sand to show the main differences. the numerical simulations are performed using a Lagrangian approach and a coupled Eulerian-Lagrangian Method (CEL), in which the simulation of large deformations is possible without problems due to mesh distortion. the method is shortly introduced. the granular soil is modelled using a hypoplastic constitutive model, thus reproducing soil effects like dilatancy, contractancy, pressure and void ratio dependent stiffness, pressure and void ratio dependent strength, different stiffness for loading, unloading and reloading paths.

关键词： Piles

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the numerical implementation of elastic visco-plastic model for soft clays

The numerical implementation of elastic visco-plastic model ...

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8th european conference on numerical methods in geotechnical engineering (NUMGE)

作者： Feng, W. Q. Li, Y. L. Yin, J. H. Yin, Z. Y. Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Hong Kong Peoples R China Shanghai Jiao Tong Univ Dept Civil Engn Shanghai Peoples R China Ecole Centrale Nantes LUNAM Univ UMR CNRS GeM Nantes France Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China PolyU Shenzhen Res Inst Shenzhen Peoples R China Shanghai Jiao Tong Univ Dept Civil Engn Shanghai Peoples R China Ecole Centrale Nantes LUNAM Univ UMR CNRS GeM Nantes France

ISBN: (纸本)9781315751825;9781138026872

A considerable progress in theoretical framework of Elastic Visco-Plastic model (EVP) has been achieved in the last decades. In order to extend these models into application, appropriate numerical algorithms for the nonlinear constitutive equations of an EVP are investigated in this study. the EVP model is incorporated into the Plaxis software. the performances of the implicit time-stepping algorithm and explicit time-stepping algorithm are examined in details. In addition, the stability and accuracy of the EVP model are studied with different algorithms are evaluated and the validation of the EVP model is examined by comparing the simulation results with previous experimental results, demonstrating a considerable agreement.

关键词： Nonlinear equations

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Modeling structural elements subjected to buckling using data mining and the finite element method 8

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International Joint conference on 8th International conference on Soft Computing Models in Industrial and Environmental Applications, SOCO 2013, 6th International conference on Computational Intelligence in Security for Information Systems, CISIS 2013 and 4th International conference on european Transnational Education, ICEUTE 2013

作者： Fernández-Martinez, Roberto Lostado-Lorza, Rubén Illera-Cueva, Marcos Donald, Bryan J. Mac Department of Material Science University of Basque Country UPV/EHU Bilbao Spain Department of Mechanical Engineering University of La Rioja Logroño Spain School of Mechanical and Manufacturing Engineering Dublin City University Dublin 9 Ireland

ISBN: (纸本)9783319018539

Buckling of thin walled welded structures is one of the most common failure modes experienced by these structures in-service. the study of such buckling, to date, has been concentrated on experimental tests, empirical models and the use of numerical methods such as the Finite Element Method (FEM). Some researchers have combined the FEM with Artificial Neural Networks (ANN) to study both open and closed section structures but these studies have not considered imperfections such as holes, weld seams and residual stresses. In this paper, we have used a combination of FEM and ANN to obtain predictive models for the critical buckling load and lateral displacement of the center of the profile under compressive loading. the study was focused on ordinary Rectangular Hollow Sections (RHS) and on the influence of geometric imperfections while taking residual stresses into consideration. © Springer International Publishing Switzerland 2014.

关键词： Buckling

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Investigation of near-wall grid spacing effect in high-order discontinuous Galerkin RANS computations of turbomachinery flows 9

Investigation of near-wall grid spacing effect in high-order...

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9th International conference on Spectral and High Order methods, ICOSAHOM 2012

作者： Bassi, F. Botti, L. Colombo, A. Ghidoni, A. Rebay, S. University of Bergamo Department of Industrial Engineering Viale Marconi 5 Dalmine Bergamo24044 Italy University of Brescia Department of Industrial and Mechanical Engineering via Branze 38 Brescia25123 Italy

ISBN: (纸本)9783319016009

In the last decade, Discontinuous Galerkin (DG) methods have been the subject of extensive research effort because of their excellent performance in the high-order accurate discretization of advection-diffusion problems on general unstructured grids, and are nowadays finding use in several different applications. In this paper, the potential offered by a high-order accurate DG space discretization method with implicit time integration for the solution of the Reynolds-averaged Navier-Stokes equations coupled with the k-ωturbulence model is investigated in the numerical simulation of the turbulent flow through the well known T106A turbine cascade. the numerical results demonstrate that, by exploiting high order accurate DG schemes, it is possible to compute accurate simulations of this flow on grids with few elements. © Springer International Publishing Switzerland 2014.

关键词： numerical methods

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