Variations in the stress state, influenced by factors like pore water pressure, temperature changes, and freezing/thawing cycles, cause strain in outcropping rock masses. Thermo-mechanical deformations in jointed rock masses can be significant at mid-latitudes, where progressive strain accumulation is controlled by local fracturing and exposure conditions. Consequently, the strain field is strongly scale-dependent. To investigate these topics, the Acuto Field Laboratory (AFL) has been operating since 2016 to investigate those natural processes governing rock mass deformation and acting as preparatory factors of rock slope instabilities. A multi-parametric monitoring system, consisting of seismic, stress-strain and thermal sensors, as well as optical cameras, was installed on a sub-vertical rock wall inside an abandoned quarry. Recent technological advancements have enabled the use of both traditional and innovative sensors, such as Fiber Bragg Grating (FBG) arrays for strain and rock temperature monitoring. Unlike traditional strain devices that provide measurement on a single point or joint, FBG arrays allow for measurements along variable-length baselines. In the case of the AFL, three FBG baselines of increasing length have been installed in three directions (i.e., vertical, horizontal, and diagonal) on a rock mass section exposed to thermal forcing, covering approximately 2 m2. The strain measured along each FBG baseline represents the cumulative deformation of the rock matrix and fractures intersecting that measuring baseline, thus providing the net strain response of the fractured rock mass. The collected measurements are currently being analysed and will be used to train an artificial neural network to investigate the relationship between environmental factors and rock mass deformations.

Multi-scale monitoring of rock mass deformations in a mid-latitude climatic context through a Fiber Bragg Grating array

Matteo Fiorucci
;
2025-01-01

Abstract

Variations in the stress state, influenced by factors like pore water pressure, temperature changes, and freezing/thawing cycles, cause strain in outcropping rock masses. Thermo-mechanical deformations in jointed rock masses can be significant at mid-latitudes, where progressive strain accumulation is controlled by local fracturing and exposure conditions. Consequently, the strain field is strongly scale-dependent. To investigate these topics, the Acuto Field Laboratory (AFL) has been operating since 2016 to investigate those natural processes governing rock mass deformation and acting as preparatory factors of rock slope instabilities. A multi-parametric monitoring system, consisting of seismic, stress-strain and thermal sensors, as well as optical cameras, was installed on a sub-vertical rock wall inside an abandoned quarry. Recent technological advancements have enabled the use of both traditional and innovative sensors, such as Fiber Bragg Grating (FBG) arrays for strain and rock temperature monitoring. Unlike traditional strain devices that provide measurement on a single point or joint, FBG arrays allow for measurements along variable-length baselines. In the case of the AFL, three FBG baselines of increasing length have been installed in three directions (i.e., vertical, horizontal, and diagonal) on a rock mass section exposed to thermal forcing, covering approximately 2 m2. The strain measured along each FBG baseline represents the cumulative deformation of the rock matrix and fractures intersecting that measuring baseline, thus providing the net strain response of the fractured rock mass. The collected measurements are currently being analysed and will be used to train an artificial neural network to investigate the relationship between environmental factors and rock mass deformations.
2025
978-82-8208-079-8
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11580/116104
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