An experimental investigation on thermal damage and failure mechanical behavior of granite after exposure to different high temperature treatments
TL;DR: In this paper, the effect of high temperature treatments (200, 300, 400, 500, 600, 700 and 800) on the crack damage, strength and deformation failure behavior of a granite was investigated.
About: This article is published in Geothermics.The article was published on 2017-01-01. It has received 406 citations till now. The article focuses on the topics: Acoustic emission & Ultimate tensile strength.
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TL;DR: In this article, the authors evaluate the thermal effects on the geophysical properties of granite and show that the dynamic strength decreases linearly as temperature increases but increases as the impact pressure increases.
212 citations
TL;DR: In this article, the thermal effects on micro-properties of granite were experimentally studied and two indexes (heterogeneity coefficient and anisotropy coefficient) were proposed to describe the micro properties of granite.
171 citations
TL;DR: In this paper, the effects of temperature on the physical properties and mechanical and permeability behavior of sandstone were analyzed, and a series of empirical relations between the temperatures and physical and mechanical properties were derived, and are expected to aid in geothermal energy extraction from super-critical temperature resources.
133 citations
TL;DR: In this article, the results from tests performed to investigate the tensile mechanical characteristics of granite after exposure to heating and cooling treatments were analyzed using the Brazilian disc method, and the results showed that the water-cooled samples exhibited the largest decrease in P-wave velocity and the largest numbers of newly generated cracks on the surface, which indicates that the samples heated and cooled at higher cooling rates were more susceptible to the heating/cooling treatments.
124 citations
TL;DR: In this article, uniaxial compression tests were conducted on granite specimens containing three non-coplanar holes and the relationships between the stress, acoustic emission (AE) and crack evolution process were analyzed using AE measuring and photographic monitoring techniques.
120 citations
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TL;DR: In this article, the failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission, and the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process.
Abstract: The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process which normally would occur violently in a fraction of a second. Using a procedure originally developed to locate earthquakes, acoustic emission arrival-time data are inverted to obtain three-dimensional locations of microseisms. These locations provide a detailed view of fracture nucleation and growth.
870 citations
TL;DR: In this article, the authors investigated the inelastic and failure behavior of six sandstones with porosities ranging from 15% to 35% and used a broad range of effective pressures to investigate the transition in failure mode from brittle faulting to cataclastic flow.
Abstract: Triaxial compression experiments were conducted to investigate the inelastic and failure behavior of six sandstones with porosities ranging from 15% to 35%. A broad range of effective pressures was used so that the transition in failure mode from brittle faulting to cataclastic flow could be observed. In the brittle faulting regime, shear-induced dilation initiates in the prepeak stage at a stress level C' which increases with effective mean stress. Under elevated effective pressures, a sample fails by cataclastic flow. Strain hardening and shear-enhanced compaction initiates at a stress level C* which decreases with increasing effective mean stress. The critical stresses C' and C* were marked by surges in acoustic emission. In the stress space, C* maps out an approximately elliptical yield envelope, in accordance with the critical state and cap models. Using plasticity theory, the flow rule associated with this yield envelope was used to predict porosity changes which are comparable to experimental data. In the brittle faulting regime the associated flow rule predicts dilatancy to increase with decreasing effective pressure in qualitative agreement with the experimental observations. The data were also compared with prediction of a nonassociative model on the onset of shear localization. Experimental data suggest that a quantitative measure of brittleness is provided by the grain crushing pressure (which decreases with increasing porosity and grain size). Geologic data on tectonic faulting in siliciclastic formations (of different porosity and grain size) are consistent with the laboratory observations.
805 citations
Journal Article•
594 citations
TL;DR: In this article, the deformation behavior of Westerly granite deformed dry at a constant strain rate of 10−6/s, confining pressures of 1.5-15 kbar, and temperatures of 25°-1000°C.
Abstract: The deformation behavior of quartz and feldspar has been studied in Westerly granite deformed dry at a constant strain rate of 10−6/s, confining pressures of 1.5–15 kbar, and temperatures of 25°–1000°C. Samples deformed at lower temperatures and pressures show throughgoing faults; those deformed at intermediate conditions show a combination of grain-scale faults and plastic deformation; and those deformed at higher temperatures and pressures show plastic deformation with no faults of any scale. On a grain scale the deformation is inhomogeneous at all conditions because of the polyphase nature of the material. Detailed petrographic and transmission electron microscope (TEM) observations have been made of the deformed specimens. The fault gouge consists of very fine grained material which verges on being amorphous, but no evidence of melt was seen. In the regions away from fault zones, there is a transition from dominantly microcracking to dominantly dislocation glide and climb; this transition is primarily a function of temperature. Dislocation motion is thermally activated and is probably almost unaffected by pressure over the range investigated. Thus at low temperature the strain rate that can be produced by dislocation motion is limited, and the difference between this and the imposed strain rate must occur by microcracking. The way in which the microcracking accomplishes the deformation depends on pressure. At low pressures (<5 kbar) the microcracks link up to form a throughgoing fault after very low strain; at higher pressures (7.5–15 kbar) they produce only grain-scale faults, ‘deformation bands,’ and undulatory extinction, and no throughgoing faults are formed after 15–20% shortening. At the laboratory strain rate of 10−6/s the transition from dominantly microcracking to dominantly dislocation motion occurs at approximately 300°–400°C for quartz and 550°–650°C for feldspar. When one allows for the slower natural strain rates and the presence of water, this grain-scale brittle-ductile transition may correspond to the limiting depth of earthquakes on strike slip faults.
390 citations
TL;DR: An extensive literature review was performed to assemble data on the following properties: modulus, Poisson's ratio, tensile strength, compressive strength, viscosity, thermal expansion, density, permeability, melting temperature, heat of fusion, specific heat, thermal conductivity and thermal diffusivity.
367 citations