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, B. B.; Hudyma, Nick

doi:10.1016/j.ijrmms.2006.06.003

Cited by 12 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The high porosity and loose cohesion of this poorly welded tuff leads to a low strength of the material [ Fuenkajorn and Daemen , 1992; Al‐Harthi et al , 1999]. The variability found for E i and UCS absolute values is strongly driven by the random distribution of the macroporosity within this lithology [ Gokceoglu , 2002; Hudyma et al , 2004; Sonmez et al , 2006; Avar and Hudyma , 2007].…”

Section: Resultsmentioning

confidence: 99%

Radon and thoron emission from lithophysae‐rich tuff under increasing deformation: An experimental study

Tuccimei

Mollo

Vinciguerra

et al. 2010

Geophysical Research Letters

View full text Add to dashboard Cite

[1] Radon and thoron emissions from lithophysae-rich tuff under increasing deformation are measured to determine how mechanical damage affects gas emission levels in tuffs. Mechanical properties of rocks under stresses should be carefully considered to properly interpret data from geochemical field monitoring. Two samples are uniaxially loaded up to failure, while two others are unloaded at the end of the elastic phase, in order to achieve the highest compaction of existing pores. Changes in the porosity of deformed samples are evidenced by helium pycnometer and microscopy analyses. Radon and thoron exhalation rates are measured on groups of two samples by alpha spectrometer technique. Results show that tuff samples are characterised by a dual porosity consisting of a macroporosity, given by isolated large pores with sizes from mm-up to cm-scale and a microporosity ranging between microns to hundreds of microns. At the end of the elastic phase pervasive pore collapse is observed, due to the closure of the cm-scale macropores. This is mirrored by a significant decrease of radon and thoron release. After failure, a further reduction of porosity in the rock adjacent to the fault planes is observed due to extensive closure of both macropores and micropores. At this stage radon and thoron emissions increase. The formation of new exhaling surfaces is the main carrier of the bulk increase of radon and thoron exhalations, strongly prevailing over the densification carried out from the compaction mechanisms. In terms of volcanic hazard, negative anomalies in radon emissions should be considered as indicators of forthcoming ruptures. Key words: radon and thoron exhalation, tuff deformation, seismic precursor. Citation: Tuccimei, P., S. Mollo, S. Vinciguerra, M. Castelluccio, and M. Soligo (2010), Radon and thoron emission from lithophysae-rich tuff under increasing deformation: An experimental study, Geophys. Res. Lett., 37, L05305,

show abstract

Section: Resultsmentioning

confidence: 99%

Radon and thoron emission from lithophysae‐rich tuff under increasing deformation: An experimental study

Tuccimei

Mollo

Vinciguerra

et al. 2010

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…It is possible that welding of the highly plastic glass shards induced by heat and overburden could result in significant geometric complexity in the pore space, such that the mechanical behavior is controlled by not only the porosity but also other microstructural attributes. Indeed it has been suggested that attributes including the nature of welding, microcrack density, as well as the presence of lithophysae, pumice and clay minerals all exert important influence on the strength of a welded tuff [ Price and Bauer , 1985; Moon , 1993a; Avar and Hudyma , 2007]. Deeper understanding of this question would require a systematic investigation of the mechanics of failure in welder tuffs, which should be pursued in future investigations even though it is beyond the scope of the present study.…”

Section: Discussionmentioning

confidence: 98%

“…Previous rock mechanics studies of tuff have mostly focused on the uniaxial compressive strength (UCS) as a geotechnical property. In particular, tuff samples from both outcrops and boreholes in Yucca Mountain, Nevada have been investigated extensively [ Nimick et al , 1985; Martin et al , 1994, 1995; Schultz and Li , 1995; Lockner and Morrow , 2008; Avar and Hudyma , 2007]. The porosity of 198 samples of ignimbrites from three boreholes at Yucca Mountain ranges from as low as 1% in the densely welded tuffs to 53% in the zeolitized nonwelded tuffs [ Nelson and Anderson , 1992].…”

Section: Discussionmentioning

confidence: 99%

“…In her comprehensive study of ignimbrite (a pyroclastic deposit or “ash flow tuff”) in New Zealand, Moon [1993a, 1993b] observed very rapid vertical variations in uniaxial compressive strength, by as much as two orders of magnitude in core samples retrieved within one vertical section. While there may be an overall trend for the strength to decrease with increasing porosity, other microstructural attributes (including the nature of welding, microcrack density, as well as the presence of lithophysae, pumice and clay minerals) seem to also exert important influence [ Price and Bauer , 1985; Moon , 1993a; Schultz and Li , 1995; Evans and Bradbury , 2004; Avar and Hudyma , 2007]. In particular, welded tuffs (the fragments of which were plastic enough when they were deposited to have been fused) may show significant variability in strength even if they have comparable porosities.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Micromechanics of brittle faulting and cataclastic flow in Alban Hills tuff

Baud¹,

Zhu²,

Vinciguerra³

et al. 2011

J. Geophys. Res.

View full text Add to dashboard Cite

[1] An understanding of how tuff deforms and fails is of importance in the mechanics of volcanic eruption as well as geotechnical and seismic applications related to the integrity of tuff structures and repositories. Previous rock mechanics studies have focused on the brittle strength. We conducted mechanical tests on nominally dry and water-saturated tuff samples retrieved from the Colli Albani drilling project, in conjunction with systematic microstructural observations on the deformed samples so as to elucidate the micromechanics of brittle failure and inelastic compaction. The phenomenological behavior was observed to be qualitatively similar to that in a porous sedimentary rock. Synthesizing published data, we observe a systematic trend for both uniaxial compressive strength and pore collapse pressure of nonwelded tuff to decrease with increasing porosity. To interpret the compaction behavior in tuff, we extended the cataclastic pore collapse model originally formulated for a porous carbonate rock to a dual porosity medium made up of macropores and micropores or microcracks.

show abstract

“…The lithophysae‐rich tuff consists of (1) matrix material, (2) vapor phase mineral rims, and (3) lithophysae, with lithophysae ranging in shape from circular to gashlike and in size from 1 to 100 cm (Figure 5, left). Testing of lithophysal rock samples showed that the presence of lithophysae causes significant variability in the elastic (Young's) modulus and in the uniaxial (unconfined) compressive strength of tuff [ Price , 2004; Avar et al , 2003; Avar and Hudyma , 2007; Damjanac et al , 2007]. Some of these laboratory tests were conducted on large core samples (267–290 mm diameter) of the Tptpul and Tptpll units extracted from the ESF and Cross Drift to be more representative of in situ conditions (Figure 5, right).…”

Section: Development Of Conceptual Understanding and Modelsmentioning

confidence: 99%

Multiphysics processes in partially saturated fractured rock: Experiments and models from Yucca Mountain

Rutqvist

Tsang

2012

Reviews of Geophysics

View full text Add to dashboard Cite

The site investigations at Yucca Mountain, Nevada, have provided us with an outstanding data set, one that has significantly advanced our knowledge of multiphysics processes in partially saturated fractured geological media. Such advancement was made possible, foremost, by substantial investments in multiyear field experiments that enabled the study of thermally driven multiphysics and testing of numerical models at a large spatial scale. The development of coupled‐process models within the project have resulted in a number of new, advanced multiphysics numerical models that are today applied over a wide range of geoscientific research and geoengineering applications. Using such models, the potential impact of thermal‐hydrological‐mechanical (THM) multiphysics processes over the long‐term (e.g., 10,000 years) could be predicted and bounded with some degree of confidence. The fact that the rock mass at Yucca Mountain is intensively fractured enabled continuum models to be used, although discontinuum models were also applied and are better suited for analyzing some issues, especially those related to predictions of rockfall within open excavations. The work showed that in situ tests (rather than small‐scale laboratory experiments alone) are essential for determining appropriate input parameters for multiphysics models of fractured rocks, especially related to parameters defining how permeability might evolve under changing stress and temperature. A significant laboratory test program at Yucca Mountain also made important contributions to the field of rock mechanics, showing a unique relation between porosity and mechanical properties, a time dependency of strength that is significant for long‐term excavation stability, a decreasing rock strength with sample size using very large core experiments, and a strong temperature dependency of the thermal expansion coefficient for temperatures up to 200°C. The analysis of in situ heater experiments showed that fracture closure/opening caused by changes in normal stress across fractures was the dominant mechanism for thermally induced changes in intrinsic fracture permeability during rock mass heating/cooling and that fracture shear dilation appears to be less significant. Significant effort was devoted to predicting the long‐term stability of underground excavations under (mechanical) strength degradation and seismic loading, perhaps one of the most challenging tasks within the project. We note that such long‐term strength degradation is actually an example of a chemically mediated process governed by underlying (microscopic) stress corrosion and chemical diffusion processes. In the Yucca Mountain Project, such chemically mediated mechanical changes were considered implicitly through model calibrations against laboratory and in situ heater experiments at temperatures anticipated to be experienced by the rock. A possible future research direction would be to simulate such processes mechanistically in a complete coupled THMC framework where C denotes chemical processes.

show abstract

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

Cited by 12 publications

References 11 publications

Radon and thoron emission from lithophysae‐rich tuff under increasing deformation: An experimental study

Radon and thoron emission from lithophysae‐rich tuff under increasing deformation: An experimental study

Micromechanics of brittle faulting and cataclastic flow in Alban Hills tuff

Multiphysics processes in partially saturated fractured rock: Experiments and models from Yucca Mountain

Contact Info

Product

Resources

About