Rock displacement and thermal expansion study at historic heritage sites in Slovakia

Vlčko, Ján; Greif, Vladimír; Grof, Vladimir; Jezny, Michal; Petro, Lubomir; Brcek, Martin

doi:10.1007/s00254-008-1672-7

Cited by 37 publications

(16 citation statements)

References 3 publications

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“…It was demonstrated that across discontinuous jointed media, primary porosity and crack density can influence the heat propagation within a rock mass and particularly affecting the surficial cooling rate at its interface [ 34 , 50 ]. Natural diurnal or annual temperature oscillations can induce long-term thermo-mechanical effects on rock masses able to influence the integrity of natural [ 51 ] or cultural heritage [ 52 , 53 ]. Moreover, numerical models of temperature distribution are useful for detecting the existence of thermally driven deformation comprising both quasi-cyclical (reversible) and irreversible (plastic) strains [ 54 ].…”

Section: Introductionmentioning

confidence: 99%

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

Fiorucci

Marmoni

Martino

2018

Sensors

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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.

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Section: Introductionmentioning

confidence: 99%

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

Fiorucci

Marmoni

Martino

2018

Sensors

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“…In addition, studies of differential weathering of boulders in arid environments [24][25][26] indicate that insolation-induced radial thermal gradients may generate tensile stresses in decimetreto metre-scale boulders. Other work verifies that some form of cyclic thermally induced deformation occurs in unstable rock masses, whether by long-term creep of detached blocks or by short-term fracture propagation in competent rock [27][28][29][30] . In only one previous study 31 has the role of thermal stress in exfoliation sheets been related to how this might trigger rockfalls.…”

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confidence: 97%

Rockfall triggering by cyclic thermal stressing of exfoliation fractures

2016

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Exfoliation of rock deteriorates cli s through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cli in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are su cient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the e cacy of other, more typical rockfall triggers. R ockfalls are common and hazardous in steep terrains around the world 1-4 , and are primary agents of landscape erosion in many environments 4-8 . In exfoliating landscapes (Fig. 1a), rockfalls frequently occur as detachments of the outer rock layers (exfoliation sheets) along surface-parallel fractures (joints). These detachments are typically thinner (measured normal to rock faces) than they are wide or long. The origin and formation of exfoliation sheets, particularly those formed in granitic landscapes, has been a subject of interest for more than a century 9-15 . The consensus that erosion-induced or palaeo-stresses are responsible for their formation has been challenged by recent work 16,17 proposing that a combination of regional compressive stresses and topographic curvature can generate exfoliation fractures. Regardless of their origin, understanding modern-day failure of rock masses along exfoliation fractures is important for studies of landscape erosion and rockfall hazards. Rockfalls can be triggered by a number of mechanisms, including precipitation, seismic shaking, and freeze-thaw conditions 6,18 . Yet many rockfalls lack recognized triggers and are seemingly spontaneous events, suggesting other factors at play. The role of thermal effects (temperature and insolation) on initiating rock deformation, where rock surfaces expand, contract, and eventually fail in response to cyclical temperature variations, was critically examined regarding exfoliation sheet formation, and subsequently dismissed 11,19,20 . However, these studies did not investigate what role thermal effects might have on the deformation of existing exfoliation sheets. Further, some studies 13 acknowledged that thermal effects could be important at depths of less than one metre-areas of obvious interest for rockfalls. Recent studies on building f...

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“…In spite of the above-mentioned limitation, cyclic LOS movements with a daily base ranging from 0.5 to 1.2 mm were detected at certain locations and tentatively attributed to the thermal variation of the rock mass due to different sunlight conditions. Cyclic movements could lead to local failures (Vlcko et al, 2009;Hatzor and Bakun Mazor, 2013) when combined with destabilizing actions (i.e., earthquakes, water pressures) or conditions (i.e., strength reduction for weathering), as suggested by the performed slope stability analyses.…”

Section: Discussionmentioning

confidence: 99%

Integrating geomechanical surveys and remote sensing for sea cliff slope stability analysis: the Mt. Pucci case study (Italy)

Martino

Mazzanti

2014

Nat. Hazards Earth Syst. Sci.

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Abstract. An integrated approach to the geomechanical characterization of coastal sea cliffs was applied at Mt. Pucci (Gargano promontory, Southern Italy) by performing fieldbased geomechanical investigations and remote geostructural investigations via a terrestrial laser scanner (TLS). The consistency of the integrated techniques allowed to achieve a comprehensive and affordable characterization of the main joint sets on the sea cliff slope. The observed joint sets were considered to evaluate the proneness of the slope to rock failures by attributing safety factor (SF) values to the toppleand wedge-prone rock blocks under three combined or independent triggering conditions: (a) hydrostatic water pressures within the joints, (b) seismic action, and (c) strength reduction due to weathering of the joint surfaces. The combined action of weathering and water pressures within the joints was also considered, resulting in a significant decrease in the stability. Furthermore, remote survey analyses via InfraRed Thermography (IRT) and Ground Based Synthetic Aperture Radar Interferometry (GBInSAR) were performed to evaluate the role of the surveyed joint sets in inducing instabilities in the Mt. Pucci sea cliff. The results from the remote surveys: (i) GBInSAR monitoring revealed permanent displacements coupled to cyclic daily displacements, these last ones detected in certain sectors of the cliff wall; (ii) the thermal images allowed us to identify anomalies that correspond well to the main joints and to the slope material released due to recent collapses.

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Rock displacement and thermal expansion study at historic heritage sites in Slovakia

Cited by 37 publications

References 3 publications

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

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

Rockfall triggering by cyclic thermal stressing of exfoliation fractures

Integrating geomechanical surveys and remote sensing for sea cliff slope stability analysis: the Mt. Pucci case study (Italy)

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