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Bharadwaj, Pawan (author), Drijkoningen, G.G. (author), Mulder, W.A. (author), Thorbecke, J.W. (author), Neducza, Boriszlav (author), Jenneskens, R (author)
In the near surface with unconsolidated soils, shear-wave properties can often be characterised better and with a higher resolution than compressional-wave properties. To enable imaging ahead of a tunnel-boring machine, we developed a seismic prediction system with a few shear-wave vibrators and horizontal receivers. The boring process is...
journal article 2017
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Bharadwaj, Pawan (author), Mulder, W.A. (author), Drijkoningen, G.G. (author)
Least-squares inversion of seismic arrivals can provide remarkably detailed models of the Earth's subsurface. However, cycle skipping associated with these oscillatory arrivals is the main cause for local minima in the least-squares objective function. Therefore, it is often difficult for descent methods to converge to the solution without an...
journal article 2016
document
Bharadwaj, Pawan (author), Drijkoningen, G.G. (author), Mulder, W.A. (author), Tscharner, Thomas (author), Jenneskens, Rob (author)
The Earth’s properties, composition and structure ahead of a tunnel boring machine (TBM) should be mapped for hazard assessment during excavation. We study the use of seismic-exploration techniques for this purpose. We focus on a seismic system for soft soils, where shear waves are better and easier to interpret than compressional waves, as has...
conference paper 2016
document
Pisupati, P.B. (author), Mulder, W.A. (author), Drijkoningen, G.G. (author)
To overcome the local minima problem in FWI, we propose to use an auxiliary data-domain objective function during inversion. It reduces the data to a simpler form by squaring, followed by blurring to ensure that events that are too far apart can still interact during the inversion. As it effectively replaces seismic arrivals by bumps, we call it...
conference paper 2015
document
Pisupati, P.B. (author), Mulder, W.A. (author), Drijkoningen, G.G. (author), Reijnen, R. (author)
In the near-surface with unconsolidated soils, shear properties can be well imaged, sometimes better than P-wave properties. To facilitate ground prediction ahead of a tunnel boring machine (TBM), active ‘surveys’ with shear-wave vibrators are carried out during boring. In such surveys, only a few shear-wave vibrators can be placed in front of...
conference paper 2015
document
Pisupati, P.B. (author), Mulder, W.A. (author), Drijkoningen, G.G. (author)
With single-parameter full waveform inversion, estimating the inverse of the Hessian matrix will accelerate the convergence, but is computationally expensive. Therefore, an approximate Hessian, which is easier to compute, is often used. Similarly, in the case of multi-parameter full waveform inversion, the computation of the Hessian terms that...
conference paper 2014
document
Bharadwaj, P. (author), Mulder, W.A. (author), Drijkoningen, G.G. (author)
Least-squares inversion of seismic reflection waveforms can reconstruct remarkably detailed models of the Earth’s subsurface. However, the cycle-skipping associated with the highfrequency waveforms are responsible for spurious local minima in its objective function. Therefore, it is often difficult for descent methods to converge to the true...
journal article 2013
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