Poisson's ratio values for rocks

Gerçek, Hasan

doi:10.1016/j.ijrmms.2006.04.011

Cited by 676 publications

(304 citation statements)

References 49 publications

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“…An appropriate value of the Poisson ratio for volcanic regions of ν = 0.25 is specified for the whole domain, except in the damage and core zones of the fault areas, where higher values (0.30 and 0.40, respectively) are specified on the basis of the nature of the rock (Gercek, 2007). Rigidity values are reduced in the fault zones (µ = 0.385 and 0.0357 GPa for the fault core and damage zone, respectively, which correspond to E = 10 9 and 10 8 , where E is the Young modulus).…”

Section: A Coco Et Al: Numerical Models For Ground Deformation and mentioning

confidence: 99%

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

et al. 2016

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Abstract. Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas).Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady-state value.Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO 2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.

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Section: A Coco Et Al: Numerical Models For Ground Deformation and mentioning

confidence: 99%

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

et al. 2016

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“…An ice thickness of 1 km thick was modelled, although the AVA response is independent of ice thickness provided that the relative range of offsets is maintained. The acoustic impedance of the dilatant till, Z dil , is 3.42 kg m −2 s −1 (Atre and Bentley, 1993;Vaughan et al, 2003) and its Poisson's ratio, σ dil , is 0.494, typical for water-saturated sediment (Gercek, 2007). Lodged till acoustic impedance, Z lod , is 3.90 kg m −2 s −1 (Atre and Bentley, 1993; Vaughan et al, 2003) and its Poisson's ratio, σ lod , is 0.32, representative of average values for granular silty soil (Gercek, 2007).…”

Section: Ray-tracing Of Reflected Travel-timesmentioning

confidence: 99%

“…The dilatant till has a maximum thickness of 2 m and a Poisson's ratio that approaches 0.5, indicating high water saturation and non-cohesive sediment (Gercek, 2007). The underlying lodged till has an acoustic impedance of 4.26 ± 0.59 × 10 6 kg m −2 s −1 , suggesting both low porosity and water saturation.…”

Section: Thin-layer Analysismentioning

confidence: 99%

Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA) analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

et al. 2012

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Abstract. Seismic amplitude-versus-angle (AVA) methods are a powerful means of quantifying the physical properties of subglacial material, but serious interpretative errors can arise when AVA is measured over a thinly-layered substrate. A substrate layer with a thickness less than 1/4 of the seismic wavelength, λ, is considered "thin", and reflections from its bounding interfaces superpose and appear in seismic data as a single reflection event. AVA interpretation of subglacial till can be vulnerable to such thin-layer effects, since a lodged (non-deforming) till can be overlain by a thin (metre-scale) cap of dilatant (deforming) till. We assess the potential for misinterpretation by simulating seismic data for a stratified subglacial till unit, with an upper dilatant layer between 0.1-5.0 m thick (λ / 120 to > λ / 4, with λ = 12 m). For dilatant layers less than λ / 6 thick, conventional AVA analysis yields acoustic impedance and Poisson's ratio that indicate contradictory water saturation. A thin-layer interpretation strategy is proposed, that accurately characterises the model properties of the till unit. The method is applied to example seismic AVA data from Russell Glacier, West Greenland, in which characteristics of thin-layer responses are evident. A subglacial till deposit is interpreted, having lodged till (acoustic impedance = 4.26 ± 0.59 × 10 6 kg m −2 s −1 ) underlying a water-saturated dilatant till layer (thickness < 2 m, Poisson's ratio ∼ 0.5). Since thin-layer considerations offer a greater degree of complexity in an AVA interpretation, and potentially avoid misinterpretations, they are a valuable aspect of quantitative seismic analysis, particularly for characterising till units.

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“…Direct 492 comparison of SRT derived Young's moduli with cone resistance at the CPT locations (Fig. 8b and c can be classified as saturated clay or sand, while below this threshold the material is more likely to 506 comprise partially saturated sand or silt (Bowles, 1988;Gercek, 2007). Applying this and comparing 507 the imaged Poisson's ratio with the geological understanding of the site (Fig.…”

Section: Poisson's Ratiomentioning

confidence: 99%

Landslide characterization using P- and S-wave seismic refraction tomography — The importance of elastic moduli

Uhlemann

Hagedorn

Dashwood

et al. 2016

Journal of Applied Geophysics

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12In the broad spectrum of natural hazards, landslides in particular are capable of changing the 13 landscape and causing significant human and economic losses. Detailed site investigations form an 14 important component in the landslide risk mitigation and disaster risk reduction process. These 15 investigations usually rely on surface observations, discrete sampling of the subsurface, and 16 laboratory testing to examine properties that are deemed representative of entire slopes. Often this 17 requires extensive interpolations and results in large uncertainties. To compliment and extend these 18 approaches, we present a study from an active landslide in a Lias Group clay slope, North Yorkshire, 19 *Revised manuscript with No changes marked Click here to view linked References UK, examining combined P-and S-wave seismic refraction tomography (SRT) as a means of providing 20 subsurface volumetric imaging of geotechnical proxies. 21The distributions of seismic wave velocities determined from SRT at the study site indicated zones 22 with higher porosity and fissure density that are interpreted to represent the extent and depth of 23 mass movements and weathered bedrock zones. Distinguishing the lithological units was facilitated 24 by deriving the Poisson's ratio from the SRT data as saturated clay and partially saturated sandy silts 25showed distinctively different Poisson's ratios. Shear and Young's moduli derived from the SRT data 26 revealed the weak nature of the materials in active parts of the landslide (i.e. 25 kPa and 100 kPa 27 respectively). The SRT results are consistent with intrusive (i.e. cone penetration tests), laboratory, 28 and additional geoelectrical data form this site. This study shows that SRT forms a cost-effective 29 method that can significantly reduce uncertainties in the conceptual ground model of geotechnical 30 and hydrological conditions that govern landslide dynamics. 31

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Poisson's ratio values for rocks

Cited by 676 publications

References 49 publications

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA) analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

Landslide characterization using P- and S-wave seismic refraction tomography — The importance of elastic moduli

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