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Introduction
Postdoctoral fellow of the Research Foundation Flanders (FWO), KU Leuven, Department of Civil Engineering, Belgium.
Francqui Foundation fellow of the Belgian American Educational Foundation (BAEF), Stanford University, Department of Mechanical Engineering, USA.
http://pietercoulier.wix.com/pcoulier
Publications
Publications (42)
Although some preconditioners are available for solving dense linear systems, there are still many matrices for which preconditioners are lacking, in particular in cases where the size of the matrix $N$ becomes very large. There remains hence a great need to develop general purpose preconditioners whose cost scales well with the matrix size $N$. In...
We investigate an efficient preconditioning of iterative methods (such as GMRES) for solving dense linear systems that follow from a boundary element method (BEM) for the 3D Helmholtz equation, focusing on the low-frequency regime. While matrix-vector products in GMRES can be accelerated through the low-frequency fast multipole method (LFFMM), the...
Inversion of sparse matrices with standard direct solve schemes is robust but computationally expensive. Iterative solvers, on the other hand, demonstrate better scalability but need to be used with an appropriate preconditioner (e.g., ILU, AMG, Gauss--Seidel) for proper convergence. The choice of an effective preconditioner is highly problem depen...
The dynamic interaction between a layered halfspace and quasi translationally invariant structures such as roads, railway tracks, tunnels, dams, and lifelines can be modelled using a computationally efficient 2.5D approach, assuming invariance of the geometry in the longitudinal direction. This assumption is not always fulfilled in practice, howeve...
This paper studies the efficiency of subgrade stiffening next to the track as a mitigation measure for railway induced vibrations by means of a two-and-a-half-dimensional coupled finite element–boundary element methodology. An analysis in the frequency–wavenumber domain for a homogeneous halfspace reveals that the block of stiffened soil next to th...
We consider an efficient preconditioner for boundary integral equation (BIE) formulations of the two-dimensional Stokes equations in porous media. While BIEs are well-suited for resolving the complex porous geometry, they lead to a dense linear system of equations that is computationally expensive to solve for large problems. This expense is furthe...
A trench can act as a barrier to ground vibration and is a potential mitigation measure for low frequency vibration induced by surface railways. However, to be effective at very low frequencies the depth required becomes impractical. Nevertheless, for soil with a layered structure in the top few metres, if a trench can be arranged to cut through th...
Radial basis function interpolation is often employed in mesh deformation algorithms for unstructured meshes, for example in fluid–structure interaction or design optimization problems. This is known to be a robust methodology that results in high quality deformed meshes. The applicability of this method to large problems is currently hampered by i...
Railway-induced ground vibration is often associated with sites with soft ground. Stiffening of the subgrade beneath the railway track is one particular measure that has potential to reduce the vibration level at such sites. However, the mechanisms behind this reduction are not well understood. Here, the effects are examined in the context of two a...
This paper discusses the design, the installation, and the experimental and numerical evaluation of the effectiveness of a stiff wave barrier in the soil as a mitigation measure for railway induced vibrations. A full scale in situ experiment has been conducted at a site in El Realengo (Spain), where a barrier consisting of overlapping jet grout col...
Inversion of sparse matrices with standard direct solve schemes is robust, but computationally expensive. Iterative solvers, on the other hand, demonstrate better scalability; but, need to be used with an appropriate preconditioner (e.g., ILU, AMG, Gauss-Seidel, etc.) for proper convergence. The choice of an effective preconditioner is highly probl...
This paper discusses the coupling of finite element (FE) and boundary element (BE) methods for the solution of transient dynamic soil-structure interaction problems in the time domain. As both the FE and the BE method impose different requirements on the time step for reasons of stability and accuracy, iterative coupling schemes are applied since t...
Railway induced vibrations and re-radiated noise in buildings can be mitigated by means of wave barriers in the soil. Numerical simulations demonstrate that a stiff wave barrier, consisting of a material that is stiffer than the surrounding medium, can be very effective if the stiffness contrast between the barrier and the medium is sufficiently la...
This paper investigates the effectiveness of a stiff wave barrier in the soil as an efficient measure for the mitigation of railway induced vibrations. Numerical calculations demonstrate that such a barrier can be very effective, provided that the stiffness contrast between the barrier and the surrounding soil is sufficiently large. Findings from t...
The numerical prediction of vibrations in buildings due to railway traffic is a complicated problem where wave propagation in the soil couples the source (railway tunnel or track) and the receiver (building). This through–soil coupling is often neglected in state-of-the-art numerical models in order to reduce the computational cost. In this paper,...
This paper discusses the coupling of finite element and fast boundary element methods for the solution of dynamic soil–structure interaction problems in the frequency domain. The application of hierarchical matrices in the boundary element formulation allows considering much larger problems compared to classical methods. Three coupling methodologie...
The effectiveness of heavy masses next to the track as a measure for the reduction of railway induced ground vibration is investigated by means of numerical simulations. It is assumed that the heavy masses are placed in a continuous row along the track forming a wall. Such a continuous wall could be built as a gabion wall and also used as a noise b...
On sites with soft ground, stiffening of the subgrade beneath railway track has been associated with a reduction inground-borne vibration. However, the mechanisms behind this reduction are not well understood. Here, the effects are examinedin the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track...
This paper presents the application of hierarchical matrices to boundary element methods for elastodynamics based on Green's functions for a horizontally layered halfspace. These Green's functions are computed by means of the direct stiffness method; their application avoids meshing of the free surface and the layer interfaces. The effectiveness of...
This paper studies the efficiency of stiff wave barriers for the mitigation of railway induced vibrations. Coupled finite element–boundary element models developed at KU Leuven and ISVR are employed; these models have been cross–validated within the EU FP7 project RIVAS (Railway Induced Vibration Abatement Solutions). A first mitigation measure con...
This paper studies the response of pipelines to vibrations induced by the operation of a pavement breaker during the rehabilitation of concrete pavements. An efficient two-and-a-half-dimensional (2.5D) formulation is employed, where the geometry of the structure and the soil is assumed to be invariant in the longitudinal direction, allowing for a F...
The vibration response of piled foundations due to ground-borne vibration produced by an underground railway is a largely-neglected area in the field of structural dynamics. However, this continues to be an important aspect of research as it is expected that the presence of piled foundations can have a significant influence on the propagation and t...