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Tunnel restoration in unstable rock masses: Numerical analysis and validation of monitoring data from innovative instrumentation
Published in Vladimir Litvinenko, EUROCK2018: Geomechanics and Geodynamics of Rock Masses, 2018
Andrea Segalini, Andrea Carri, Roberto Savi, Edoardo Cavalca, Carlo Alessio, Georgios Kalamaras
In order to solve the first problem, a new de-spike filter has been developed and applied successfully. In particular, this subroutine excludes spike noise using phase-space method, based on modified Goring and Nikora (2002) algorithm developed by Mori et al. (2007) and then modified by Ulanowski (2014). This algorithm identifies and deletes the noise due to vibrations, using an adequate sample period and data set. The filter is sensitive to border effects and therefore should not be applied to the first N data of the data set. The noise due to vibrations will affect them: this only determines punctual unreliable results but does not influence the trend of displacements (Figure 1b). After a series of parametric analysis, a value of N equal to 40 was found appropriate for the described monitoring sample period.
Objective phase-space identification of coherent turbulent structures in 1D time series
Published in Journal of Hydraulic Research, 2022
Jiayi Wu, Andrew Nichols, Anton Krynkin, Martin Croft
Phase-space coherent structure detection is an objective way to detect structures with no ambiguity in choosing the threshold value.The phase-space detected binary series is statistically comparable with U-level detected result. These two methods usually detect events in the same groups, but do differ slightly. Over 67% of data points can be detected by both methods or not detected by both methods.Turbulent event parameters can be obtained through the phase-space detected binary series and are comparable with U-level results.The relation between turbulent event parameters (the size of turbulent structures as well as number of structures per metre) and flow conditions can be observed by the proposed method.The phase-space method accounts for the physical reality that a coherent structure consists of extremes in velocity, acceleration and jerk, and that these properties should be considered together when identifying extreme behaviour.