Thermal Response of Jointed Rock Masses Inferred from Infrared Thermographic Surveying (Acuto Test-Site, Italy)

Abstract

The Mediterranean region is affected by considerable daily and seasonal temperature variations due to intense solar radiation. In mid-seasons, thermal excursions can exceed tens of degrees thus influencing the long-term behaviour of jointed rock masses acting as a preparatory factor for rock slope instabilities. In order to evaluate the thermal response of a densely jointed rock-block, monitoring has been in operation since 2016 by direct and remote sensing techniques in an abandoned quarry in Acuto (central Italy). Monthly InfraRed Thermographic (IRT) surveys were carried out on its exposed faces and along sections of interest across monitored main joints. The results highlight the daily and seasonal cyclical behaviour, constraining amplitudes and rates of heating and cooling phases. The temperature time-series revealed the effect of sun radiation and exposure on thermal response of the rock-block, which mainly depends on the seasonal conditions. The influence of opened joints in the heat propagation is revealed by the differential heating experienced across it, which was verified under 1D and 2D analysis. IRT has proved to be a valid monitoring technique in supporting traditional approaches, for the definition of the surficial temperature distribution on rock masses or stone building materials.

Thermo-Physical and Geo-Mechanical Characterization of Faulted Carbonate Rock Masses (Valdieri, Italy)

“…Reference [14] resume an interesting application, such as the study of heat capacity of rocky walls and monitoring of waste disposal sites. Moreover, some authors [15][16][17] used IRT to characterize the thermal response of rocks and joints, as well as landslide mapping [18][19][20][21]. On the other hand, TC measurement techniques are usually applied in engineering to test buildings materials, such as concrete and insulations [22], in the electronics industry [23], in developing new materials (e.g., nanomaterials and polymers, [24]), and for fire prevention [25].…”

Environmental forcings and micro-seismic monitoring in a rock wall prone to fall during the 2018 Buran winter storm

“…5 and 6). Given the sudden temperature decrease, it is possible to assume that the snowfalls were associated with the favoured cooling and subsequent freezing of the water-permeated joints, at least in the external thermal active layer (i.e., the first 8 cm from the surface; Fiorucci et al 2018;Marmoni et al 2020), as demonstrated by the negative temperature values recorded by the thermometer within the rock mass. However, no instrumental constraints on the wetness conditions of joints are available to date.…”

“…In addition to this permanent monitoring system, an array of seismic sensors was temporarily installed before the expected drop in temperature related to the incoming intense meteorological event. On 23 February 2018, 6 Bruel & Kjaer one-component accelerometers (type 8344: frequency range 0.2-3000 Hz, sensitivity 250 mV/ms −2 ) were deployed on the sides of the protruding monitored rock block, spaced 15-20 cm apart along a horizontal alignment across major-and micro-joints over a space corresponding to the daily thermal active layer (Fiorucci et al 2018;Marmoni et al 2020). These sensors were tightened to studs previously fixed within the rock mass to ensure the best coupling with the rock mass matrix.…”

“…To study the complex interactions between meteorological forcings acting within rock masses and induced deformations, a permanent multi-sensor strain and environmental monitoring system was installed in a Field Laboratory located in an abandoned quarry and managed by the Department of Earth Sciences and the Research Centre for Geological Risks (CERI) of the University of Rome "Sapienza". This monitoring system focuses on a 20 m 3 protruding rock block that is kinematically predisposed to evolve towards failure and is sensitive to cyclical thermomechanical stress (Fiorucci et al 2018). During an intense meteorological perturbation forecasted for the end of February 2018, during which a drastic drop of temperature associated with intense rain and snowfall was expected, an accelerometer array was installed to temporarily integrate with the permanent environmental monitoring system.…”

Combining Ground Based Remote Sensing Tools for Rockfalls Assessment and Monitoring: The Poggio Baldi Landslide Natural Laboratory

“…According to [ 14 ], along the Italian mountain ranges (Alps and Apennines), fast moving landslides such as rockfalls caused the largest number of deaths. As demonstrated in recent studies [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], surveying and monitoring activities play a key role in rockfall hazard assessment and are therefore of paramount importance for the preservation of human life. As rockfalls occur in very steep slopes sometimes showing limited precursor signals [ 24 , 25 , 26 , 27 , 28 , 29 ], their investigations, as well as their prediction and stabilisation, could face many difficulties [ 30 ].…”