1887

Abstract

The near-surface geology of many regions of the Arabian Peninsula is dominated by karstic carbonate and, consequently, construction projects in the Peninsula can be adversely affected by cavities and sinkholes. The risk posed by potential cavity collapse is often mitigated by grouting, although their initial detection and characterisation is facilitated by geophysical survey. Typically, resistivity, microgravity and surface-wave seismic methods are applied to cavity detection. In this paper, we extend the use of these geophysical methods to time-lapse applications, in which the remediation of the cavity is monitored during and after the grouting operation. Furthermore, we explore the potential for ground penetrating radar (GPR) methods to complement the established suite of cavity-detection methods. These are potentially powerful in time-lapse applications since data acquisition rates are very high. We simulate GPR and resistivity acquisitions over a simple cavity geometry, which comprises two interconnected rectangular sections, and investigate the potential to a) image the fine-scale detail of the cavity, and b) monitor the progress of the grouting operation. GPR models consider common offset antennas, of 250 MHz centre-frequency; resistivity models comprise 96 electrodes installed at 0.3 m intervals, used in a Wenner array configuration. Resistivity data lack the vertical and spatial resolution to monitor the remediation during grouting, but do provide useful before-and-after snapshots of the cavity. By contrast, the GPR wavelet is easily able to resolve the shrinking air-gap inside the cavity as the grout is injected. We hope to extend these synthetic analyses to a real-data application, and consider the use of multiple data sources in a constrained inversion strategy.

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/content/papers/10.3997/2214-4609.20131867
2013-11-24
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.20131867
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