Preprints
https://doi.org/10.5194/esurf-2021-36
https://doi.org/10.5194/esurf-2021-36

  06 May 2021

06 May 2021

Review status: this preprint is currently under review for the journal ESurf.

Short Communication: Ambient Vibration Modal Analysis of Rock Arches using Enhanced Frequency Domain Decomposition and Covariance-driven Stochastic Subspace Identification

Mauro Häusler1, Paul R. Geimer2, Riley Finnegan2, Donat Fäh1, and Jeffrey R. Moore2 Mauro Häusler et al.
  • 1Swiss Seismological Service, ETH Zurich, Zurich, 8092, Switzerland
  • 2Department of Geology and Geophysics, University of Utah, Salt Lake City, 84112, USA

Abstract. Natural rock arches are rare and beautiful geologic landforms with important cultural value. As such, their management requires periodic assessment of structural integrity to understand environmental and anthropogenic influences on arch stability. Measurements of passive seismic vibrations represent a rapid and non-invasive technique to describe the dynamic properties of natural arches, including resonant frequencies, modal damping ratios, and mode shapes, which can be monitored over time for structural health assessment. However, commonly applied spectral analysis tools are often limited in their ability to resolve characteristics of closely spaced or complex higher-order modes. Therefore, we investigate two algorithms well-established in the field of civil engineering through application to a set of natural arches previously characterized using conventional seismological techniques. Results from enhanced frequency domain decomposition and parametric covariance-driven stochastic subspace identification modal analyses showed generally good agreement with spectral peak-picking and frequency-dependent polarization analyses. However, we show that these advanced techniques offer the capability to resolve closely spaced modes and provide stable damping estimates. In addition, due to preservation of phase information, enhanced frequency domain decomposition allows for direct and convenient three-dimensional visualization of mode shapes. These advanced techniques provide more detailed characterization of dynamic parameters, which can be monitored to detect structural changes indicating damage and failure, and in addition have the potential to improve numerical models used for arch stability assessment. Results of our study encourage broad adoption and application of these advanced modal analysis techniques for dynamic analysis of a wide range of geological features.

Mauro Häusler et al.

Status: open (until 28 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2021-36', Anonymous Referee #1, 04 Jun 2021 reply
  • RC2: 'Comment on esurf-2021-36', Anonymous Referee #1, 07 Jun 2021 reply
  • RC3: 'Comment on esurf-2021-36', Anonymous Referee #2, 10 Jun 2021 reply
  • EC1: 'Comment on esurf-2021-36', Jens Turowski, 11 Jun 2021 reply

Mauro Häusler et al.

Mauro Häusler et al.

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Short summary
Natural rock arches are valued landmarks worldwide. As ongoing erosion can lead to rockfall and collapse, it is important to monitor the structural integrity of these landforms . One suitable technique involves measurements of resonance, produced when mainly natural sources, such as wind, vibrate the spans. Here we explore the use of two advanced processing techniques to accurately measure the resonant frequencies, damping ratios, and deflection patterns of several rock arches in Utah, USA.