Compressive strength and failure modes of lithophysae-rich Topopah Spring Tuff specimens and analog models containing cavities

Hudyma, Nick; Avar, B. B.; Karakouzian, Moses

doi:10.1016/j.enggeo.2004.01.003

Cited by 46 publications

(20 citation statements)

References 21 publications

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“…We have chosen TRSN because the relationship between radon emission and tuff deformation of Figure 2. Schematic overview of the relationship between TRSN sample deformation and radon emission as determined by previous studies (Hudyma et al, 2004;Tuccimei et al, 2006Tuccimei et al, , 2009Tuccimei et al, , 2011. Back-scattered electron (BSE) images were obtained using a fieldemission scanning electron microscopy (FE-SEM) at the HP-HT Laboratory of Experimental Volcanology and Geophysics of the Istituto Nazionale di Geofisica e Vulcanologia in Rome (Italy).…”

Section: Testing Materialsmentioning

confidence: 98%

“…centimetre-scale cavities formed by trapped pockets of gas within the cooling volcanic ash. Generally, larger cavities are the main source of porosity and their variability in size and shape were seen to control the radon exhalation (Tuccimei et al, 2006) and mechanical properties of lithophysal tuff (Hudyma et al, 2004). Due to the presence of a high number of pores, TRSN is extremely weak with an uniaxial compressive strength (UCS; i.e.…”

Section: Testing Materialsmentioning

confidence: 99%

See 1 more Smart Citation

Real-time setup to measure radon emission during rock deformation: implications for geochemical surveillance

Tuccimei

Mollo

Soligo

et al. 2015

Geosci. Instrum. Method. Data Syst.

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Abstract.Laboratory experiments can represent a valid approach to unravel the complex interplay between the geochemical behaviour of radon and rock deformation mechanisms. In light of this, we present a new real-time experimental setup for analysing in continuum the alpha-emitting 222 Rn and 220 Rn daughters over variable stress-strain regimes. The most innovative segment of this setup consists of the radon accumulation chamber obtained from a tough and durable material that can host large cylindrical rock samples. The accumulation chamber is connected, in a closed-loop configuration, to a gas-drying unit and to a RAD7 radon monitor. A recirculating pump moves the gas from the rock sample to a solid-state detector for alpha counting of radon and thoron progeny. The measured radon signal is enhanced by surrounding the accumulation chamber with a digitally controlled heating belt. As the temperature is increased, the number of effective collisions of radon atoms increases favouring the diffusion of radon through the material and reducing the analytical uncertainty. The accumulation chamber containing the sample is then placed into a uniaxial testing apparatus where the axial deformation is measured throughout a linear variable displacement transducer. A dedicated software allows obtaining a variety of stress-strain regimes from fast deformation rates to long-term creep tests. Experiments conducted with this new real-time setup have important ramifications for the interpretation of geochemical anomalies recorded prior to volcanic eruptions or earthquakes.

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Section: Testing Materialsmentioning

confidence: 98%

Section: Testing Materialsmentioning

confidence: 99%

Real-time setup to measure radon emission during rock deformation: implications for geochemical surveillance

Tuccimei

Mollo

Soligo

et al. 2015

Geosci. Instrum. Method. Data Syst.

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“…Although it is technically incomplete to comment on failure patterns of tuff specimens by only observing failure in unconfined compression tests and not investigating the effects of confining pressure and elevated temperatures, the failure mechanism noted during testing of the cubic specimens was cavity collapse. Additionally, failure mechanisms changed with increasing porosities [14].…”

Section: Failure Mechanismmentioning

confidence: 99%

“…It is assumed that samples taken from outcrops exhibit similar material and mechanical properties to those sampled from boreholes within the tunnels. The modulus and strength values were already presented in Avar et al [13] and Hudyma et al [14]. Price [11] performed additional tests on larger size cylindrical specimens, three from the lower lithophysae zone and six from the upper lithophysae zone (length to diameter ratio varies from approximately 1.7 to 2) also taken from outcrops near Yucca Mountain [11].…”

Section: Test Datamentioning

confidence: 99%

Observations on the influence of lithophysae on elastic (Young's) modulus and uniaxial compressive strength of Topopah Spring Tuff at Yucca Mountain, Nevada, USA

Avar

Hudyma

2007

International Journal of Rock Mechanics and Mining Sciences

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“…As alteration occurs the porosity within a sample can increase or decrease through mass transfer with dissolution and precipitation of minerals as the fluids permeate through the rocks, thereby creating or infilling voids (Ferry, 1979;Giggenbach, 1984;Henneberger and Browne, 1988;Reyes, 1990;Simmons and Browne, 2000;Esmaeily et al, 2012). The pore structure is dependent on numerous factors such that the porosity within a rock can vary greatly (Hudyma et al, 2004;Heap et al, 2014b). Porosity is an important factor in rock strength, because voids reduce the integrity of the material and, as indicated by the ISRM (Ulusay and Hudson, 2007a), even a small volume of pores can have a noticeable mechanical effect (Sammis and Ashby, 1986;Fakhimi and Gharahbagh, 2011;Heap et al, 2014aHeap et al, , 2014b.…”

Section: Porosity (φ)mentioning

confidence: 99%

The development and application of the alteration strength index equation

Wyering

Villeneuve

Wallis

et al. 2015

Engineering Geology

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We have developed an alteration strength index (ASI) equation to address the effect of hydrothermal alteration on mechanical rock properties. This equation can be used to estimate a range of rock strengths, comparable to uniaxial compressive strength (UCS), based on rapid analysis of mineralogy and microstructure. We used rock samples from three geothermal fields in the Taupo Volcanic Zone (TVZ) to represent a range of alteration types. These are sedimentary, intrusive and extrusive rocks, typical of geothermal systems, from shallow and deep boreholes (72 measured Depth (mD) to 3280 mD). The parameters used in ASI were selected based on literature relating these aspects of mineralogy and microstructure to rock strength. The parameters in ASI define the geological characteristics of the rock, such as proportions of primary and secondary mineralogy, individual mineral hardness, porosity and fracture number. We calibrated the ASI against measured UCS for our samples from the TVZ to produce a strong correlation (R 2 of 0.86), and from this correlation we were able to derive an equation to convert ASI to UCS. Because the ASI-UCS relationship is based on an empirical fit, the UCS value that is obtained from conversion of the ASI includes an error of 7 MPa for the 50th percentile and 25 MPa for the 90th percentile with a mean error of 11 MPa. A sensitivity analysis showed that the mineralogy parameter is the dominant characteristic in this equation, and the ASI equation using only mineralogy can be used to provide an estimated UCS range, although the error (or uncertainty) becomes greater. This provides the ability to estimate strength even when either fracture or porosity information are not available, for example in the case of logging drill cuttings. This research has also allowed us to provide ranges of rock strengths based solely on the alteration zones, mineralogy, and depth of lithol-ogies found in a typical geothermal field that can be used to update conceptual models of geothermal fields.

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Compressive strength and failure modes of lithophysae-rich Topopah Spring Tuff specimens and analog models containing cavities

Cited by 46 publications

References 21 publications

Real-time setup to measure radon emission during rock deformation: implications for geochemical surveillance

Real-time setup to measure radon emission during rock deformation: implications for geochemical surveillance

Observations on the influence of lithophysae on elastic (Young's) modulus and uniaxial compressive strength of Topopah Spring Tuff at Yucca Mountain, Nevada, USA

The development and application of the alteration strength index equation

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