Innovative laboratory testing

Lau, J S O; Chandler, N.

doi:10.1016/j.ijrmms.2004.09.008

Cited by 108 publications

(62 citation statements)

References 19 publications

(36 reference statements)

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“…In general, for all three rock types, static Young's modulus decreased by 10-30% and Poisson's ratio increased by up to a couple of hundred per cent (Heap et al, 2010; see also Eberhardt et al, 1999;Lau and Chandler, 2004). Mechanical stresses have also been shown to reduce dynamic Young's modulus by a similar percentage (e.g., Ayling et al, 1995).…”

Section: Accepted M Manuscriptmentioning

confidence: 90%

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Heap

Mollo

Vinciguerra

et al. 2013

Journal of Volcanology and Geothermal Research

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The physical integrity of a sub-volcanic basement is crucial in controlling the stability of a volcanic edifice. For many volcanoes, this basement can comprise thick sequences of carbonates that are prone to significant thermally-induced alteration. These debilitating thermal reactions, facilitated by heat from proximal magma storage volumes, promote the weakening of the rock mass and likely therefore encourage edifice instability. Such instability can result in slow, gravitational spreading and episodic to continuous slippage of unstable flanks, and may also facilitate catastrophic flank collapse. Understanding the propensity of a particular sub-volcanic basement to such instability requires a detailed understanding of the influence of high temperatures on the chemical, physical, and mechanical properties of the rocks involved. The juxtaposition of a thick carbonate substratum and magmatic heat sources makes Mt. Etna volcano an ideal candidate for our study. We investigated experimentally the effect of temperature on two carbonate rocks that have been chosen to represent the deep, heterogeneous sedimentary substratum under Mt. Etna volcano. This study has demonstrated that thermalstressing resulted in a progressive and significant change in the physical properties of the two rocks. Porosity, wet (i.e., water-saturated) dynamic Poisson's ratio and wet Vp/Vs ratio all increased, whilst P-and S-wave velocities, bulk sample density, dynamic and static Young's modulus, dry Vp/Vs ratio, and dry dynamic Poisson's ratio all decreased. At temperatures of 800 °C, the carbonate in these rocks completely dissociated, resulting in a total mass loss of about 45% and the release of about 44 wt.% of CO 2 . Uniaxial deformation experiments showed that high in-situ temperatures (> 500°C) significantly reduced the strength of the carbonates and altered their deformation behaviour. Above 500 °C the rocks deformed in a ductile manner and A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTthe output of acoustic emissions was greatly reduced. We speculate that thermally-induced weakening and the ductile behaviour of the carbonate substratum could be a key factor in explaining the large-scale deformation observed at Mt. Etna volcano. Our findings are consistent with several field observations at Mt. Etna volcano and can quantitatively support the interpretation of (1) the irregularly low seismic velocity zones present within the sub-volcanic sedimentary basement, (2) the anomalously high CO 2 degassing observed, (3) the anomalously high Vp/Vs ratios and the rapid migration of fluids, and (4) the increasing instability of volcanic edifices in the lifespan of a magmatic system. We speculate that carbonate sub-volcanic basement may emerge as one of the decisive fundamentals in controlling volcanic stability.

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Section: Accepted M Manuscriptmentioning

confidence: 90%

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Heap

Mollo

Vinciguerra

et al. 2013

Journal of Volcanology and Geothermal Research

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“…The driving stress-ratio has been defined as the axially applied stress level, at a particular stage in the test, normalized to the average UCS (so-called instantaneous response measured according to ISRM, 1979 standards) and has been used by many other researchers (Schmidtke and Lajtai, 1985;Lajtai et al 1991;Lau and Chandler, 2004;Potyondy, 2007;Damjanac and Fairhurst, 2010) to present long-term (time-dependent) testing results acquired from creep tests.…”

Section: Defining Strain Thresholdsmentioning

confidence: 99%

The three stages of stress relaxation - Observations for the time-dependent behaviour of brittle rocks based on laboratory testing

Paraskevopoulou

Perras

Diederichs

et al. 2017

Engineering Geology

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“…Volumetric strain is developed in the positive direction and inflection point is shown in the range of 65-85% percent of maximum longitudinal contraction strain, then path of volumetric strain is changed to the negative direction after this inflection point [6]. In this study, the strains in the positive direction refer to the decease of total volume while the strains of negative direction mean the increase of total volume.…”

Section: Volumetric Strainsmentioning

confidence: 82%

Experimental Tests of Composite Material Used for Compression Joints in Thermal Bridge Breaker Systems

Kim¹,

Choi²,

Shin³

2014

IJET

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Abstract-It is important to eliminate thermal bridge for achieving passive and environmental-friendly buildings. Structural members may frequently act as thermal bridges that become a conduit of energy. A thermal bridge breaker (TBB) system is effective to reduce energy transfer between inside and outside of a building. In order to be used for a structural member, the structural capacity of a TBB system should be larger than a demand resulting from external loads. This study concentrated on the development of a TBB system that will be applicable to connection between interior and exterior floors. The developed TBB system consists of anchorage devices and compression joints. The anchorage devices are used to ensure the continuity of reinforcements in inside and outside floors while the compression joints are used to resist compression stress occurring to the TBB system. Significantly high compressive stresses are usually applied to the compression joints since they are designed with relatively small section areas. This study carried out compressive tests of composite material which is developed to be used for compression joints in a TBB system. Based on test results, TBB systems are designed for the application of a typical floor system. Index Terms-Thermal bridge breakers, compression joints, composite material, compressive tests.

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Innovative laboratory testing

Cited by 108 publications

References 19 publications

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

The three stages of stress relaxation - Observations for the time-dependent behaviour of brittle rocks based on laboratory testing

Experimental Tests of Composite Material Used for Compression Joints in Thermal Bridge Breaker Systems

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