Geomechanical characterization of volcanic rocks using empirical systems and data mining techniques

Miranda, Tiago F. S.; Sousa, L. R.; Gomes, António Topa; Tinoco, Joaquim Agostinho Barbosa; Ferreira, Cristiana

doi:10.1016/j.jrmge.2017.11.003

Cited by 24 publications

(13 citation statements)

References 19 publications

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“…If the porosity (or density) of a rock considered representative of the volcano or volcano domain is known, but the GSI is unknown, then we first recommend that the intact Young's modulus be estimated as described above. In the absence of site investigations to determine a representative GSI value, we propose herein that a GSI of 55 likely best represents the structure of a volcanic rock mass (Figure 15), which are typically highly fractured (e.g., Moon et al, 2005;Apuani et al, 2005aApuani et al, , 2005bdel Potro and Hürlimann, 2008;Justo et al, 2010;Schaefer et al, 2013;Miranda et al, 2018). A GSI of 55 is typical of a "very blocky" rock mass with a "good" to "fair" structure quality, as defined by our volcanic GSI chart (Figure 13).…”

Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 95%

“…As a result, these two categories are excluded in our GSI scheme for volcanic rock masses (Figure 13). In any case, most volcanic rock outcrops typically range somewhere between blocky (GSI = 65-85) and disintegrated (GSI = 20-40) (Figure 13; Moon et al, 2005;Apuani et al, 2005aApuani et al, , 2005bdel Potro and Hürlimann, 2008;Justo et al, 2010;Schaefer et al, 2013;Miranda et al, 2018).…”

Section: Presentation Of the Hoek-diederichs Equationmentioning

confidence: 99%

“…The GSI is a number from 0 to 100, where 0 represents an essentially cohesionless rock mass and 100 represents a pristine (fracture-free) rock mass (Figure 13). Since volcanic rock masses are typically fractured and often disturbed, estimates of their GSI have been found within the range 8-80 (Moon et al, 2005;Apuani et al, 2005aApuani et al, , 2005bdel Potro and Hürlimann, 2008;Justo et al, 2010;Schaefer et al, 2013;Miranda et al, 2018) and are in agreement with values of Rock Mass Rating (RMR), another metric for describing the structure of a rock mass, found for volcanic rock masses (Watters et al, 2000;Okubo, 2004;Thomas et al, 2004). Schaefer et al (2013), for example, found GSI values of 8-20 and 45-60 for, respectively, pyroclastic rocks and lavas and lava breccias from Pacaya volcano.…”

Section: Presentation Of the Hoek-diederichs Equationmentioning

confidence: 99%

“…To illustrate the influence of rock mass structure on the Young's modulus of a volcanic rock mass, we chose here a GSI value of 55 (a value that we consider represents a reasonable average for lavas and lava breccias; Moon et al, 2005;Apuani et al, 2005aApuani et al, , 2005bdel Potro and Hürlimann, 2008;Justo et al, 2010;Schaefer et al, 2013;Miranda et al, 2018). We consider that, without prior knowledge of the structure of a volcanic rock mass, a GSI of 55 represents a reasonable estimate.…”

Section: Estimating the Young's Modulus Of A Fractured Volcanic Rock Massmentioning

confidence: 99%

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Towards more realistic values of elastic moduli for volcano modelling

Heap

Villeneuve

Albino

et al. 2020

Journal of Volcanology and Geothermal Research

128

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Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 95%

Section: Presentation Of the Hoek-diederichs Equationmentioning

confidence: 99%

Section: Presentation Of the Hoek-diederichs Equationmentioning

confidence: 99%

Section: Estimating the Young's Modulus Of A Fractured Volcanic Rock Massmentioning

confidence: 99%

See 2 more Smart Citations

Towards more realistic values of elastic moduli for volcano modelling

Heap

Villeneuve

Albino

et al. 2020

Journal of Volcanology and Geothermal Research

128

View full text Add to dashboard Cite

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“…represents an essentially cohesionless rock mass and 100 represents a pristine (fracture-free) rock mass ( Figure 13). Since volcanic rock masses are typically fractured and often disturbed, estimates of their GSI have been found within the range 8-80 (Moon et al, 2005;Apuani et al, 2005aApuani et al, , 2005bdel Potro and Hürlimann, 2008;Justo et al, 2010;Schaefer et al, 2013;Miranda et al, 2018) and are in agreement with values of Rock Mass Rating (RMR), another metric for describing the structure of a rock mass, found for volcanic rock masses (Watters et al, 2000;Okubo, 2004;Thomas et al, 2004). Schaefer et al (2013), for example, found GSI values of 8-20 and 45-60 for, respectively, pyroclastic rocks and lavas and lava breccias from Pacaya volcano.…”

Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 99%

Towards more realistic values of elastic moduli for volcano modelling

Heap¹,

Villeneuve

Albino

et al. 2020

Preprint

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Highlights We provide porosity-Young's modulus data for 276 volcanic rock samples. We present a method to upscale these laboratory measurements to the rock mass scale. Young's modulus of a typical volcanic rock mass is 5.4 GPa. We provide methods to estimate depth-dependent rock mass Young's modulus. We provide a Microsoft Excel© spreadsheet with the relevant data and equations. J o u r n a l P r e -p r o o f AbstractThe accuracy of elastic analytical solutions and numerical models, widely used in volcanology to interpret surface ground deformation, depends heavily on the Young's modulus chosen to represent the medium. The paucity of laboratory studies that provide Young's moduli for volcanic rocks, and studies that tackle the topic of upscaling these values to the relevant lengthscale, has left volcano modellers ill-equipped to select appropriate Young's moduli for their models. Here we present a wealth of laboratory data and suggest tools, widely used in geotechnics but adapted here to better suit volcanic rocks, to upscale these values to the scale of a volcanic rock mass. We provide the means to estimate upscaled values of Young's modulus, Poisson's ratio, shear modulus, and bulk modulus for a volcanic rock mass that can be improved with laboratory measurements and/or structural assessments of the studied area, but do not rely on them. In the absence of information, we estimate upscaled values of Young's modulus, Poisson's ratio, shear modulus, and bulk modulus for volcanic rock with an average porosity and an average fracture density/quality to be 5.4 GPa, 0.3, 2.1 GPa, and 4.5 GPa, respectively. The proposed Young's modulus for a typical volcanic rock mass of 5.4 GPa is much lower than the values typically used in volcano modelling. We also offer two methods to estimate depth-dependent rock mass Young's moduli, and provide two examples, using published data from boreholes within Kīlauea volcano (USA) and Mt. Unzen (Japan), to demonstrate how to apply our approach to real datasets. It is our hope that the data and analysis presented herein will assist in the selection of elastic moduli for volcano modelling. To this end, we provide a Microsoft Excel© spreadsheet containing the data and necessary equations to calculate rock mass elastic moduli that can be updated when new data become available. The selection of the most appropriate elastic moduli will provide the most accurate model predictions and therefore the most reliable information regarding the unrest of a particular volcano or volcanic terrain. J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o fMagma". The experimental data presented in this study are, for the most part, unpublished data that were collected during mechanical studies performed in collaboration with many scientists. Although non-exhaustive, we thank

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