Influence of Environment on Brittle Fracture of Silica

Hammond, Michele; Ravitz, S. Frederick

doi:10.1111/j.1151-2916.1963.tb11740.x

Cited by 47 publications

(13 citation statements)

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“…To date, many mechanisms have been proposed to explain the water-induced strength reduction, such as fracture energy reduction [6,33,34], chemical and physical deterioration [35][36][37][38], pore pressure increase [39,40], capillary tension decrease [41] and frictional reduction [42][43][44][45][46]. Several mechanisms may act concurrently to control the deformation of wet rocks.…”

Section: Introductionmentioning

confidence: 99%

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

et al. 2019

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The presence of water strongly affects rock properties and would be related to a series of geological disasters. To understand water saturation effects on the mechanical behavior of different rock types and interpret the underlying mechanisms of differences in water sensitivity, three kinds of rocks, namely sandstone, granite and marble, were selected for tests. Uniaxial compression experiments were conducted on specimens under oven-dried and water-saturated conditions. Acoustic emission (AE) techniques were also applied to monitor and record AE signals during tests. Experimental results reveal that water weakens the mechanical parameters of the three tested rocks, such as uniaxial compressive strength (UCS), elastic modulus and critical strain. The sandstone undergoes the greatest weakening with the addition of pore water, the mechanical properties of the granite exhibit relatively minor reductions, while the marble is the least affected by water saturation. The water-weakening degree of rock properties depends on the porosity as well as the mineralogy, especially the proportion of quartz and swelling clays. Moreover, after water saturation, the failure pattern of the sandstone and the granite tends to transform into the shear-dominant mode from the tensile one in dry state, probably due to frictional reduction. However, the water presence does not change the failure mode of the marble.

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Section: Introductionmentioning

confidence: 99%

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

et al. 2019

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“…Introduction.-Water in the environment is well known to affect the mechanical strength of glass [1,2]; the strength measured in water is about one half of that measured in vacuum [3], and the strength decreases with increasing loading time (static fatigue) and with decreasing stress rate (dynamic fatigue) [4]. On the other hand, very little is known about the effect of water in glass on its mechanical strength.…”

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confidence: 99%

Dynamic Fatigue of Sodium-Silicate Glasses With High Water Content

Ito

Tomazawa

1982

J. Phys. Colloques

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Résumé.-On étudie la manière dont dépend la résistance mécanique de la vitesse d'application des contraintes pour un verre de silicate de sodium ayant un contenu en eau élevé (jusqu'à 25% en poids) . Les verres ont été préparés par séchage de la solution commerciale de silicate de sodium dans un four ou dans un autoclave. La résistance mécanique a été mesurée par une méthode de flexion en quatre points pour des vitesses d'application des charges différentes. Ces verres ont montré une forte dépendance de la vitesse, même dans l'huile de paraffine sèche ; elle augmente avec la teneur en eau. La valeur de n, mesure de cette dépendance est approximativement 5 pour les verres avec ^ 25% en poids d'eau. Parallèlement, le module d'Young décroit. On suggère que cette dépendance accrue résulte du mouvement d'eau sous l'action des contraintes appliquées. De plus, la valeur apparente du module d'Young décroit avec la vitesse de charge. Ce phénomène est expliqué par les propriétés visco-élas-tiques des verres.Abstract.-The stress-rate dependency of the mechanical strength of sodium silicate glass with high water content (up to ^25% by weight) was investigated. The glasses were prepared by drying commercial sodium silicate solution in an oven or an autoclave. The mechanical strength of the glasses was measured by a four point bending method at various stress rates. These glasses showed a strong stress rate dependency even in dired paraffin oil and the dependency increased with increasing water content; the value of n, a measure of the stress rate dependency, was approximately 5 for glasses with ^25 wt% water. At the same time Young's modulus decreased with increasing water, content. It is suggested that stress-induced motion of water is responsible for the increased stress rate dependency. In addition, the apparent value of Young's modulus decreased with decreasing stress rate. This phenomenon was explained in terms of the visco-elastic property of the glasses.1. Introduction.-Water in the environment is well known to affect the mechanical strength of glass [1,2]; the strength measured in water is about one half of that measured in vacuum [3], and the strength decreases with increasing loading time (static fatigue) and with decreasing stress rate (dynamic fatigue) [4]. On the other hand, very little is known about the effect of water in glass on its mechanical strength. Recently, Wu [5] reported some data showing that the elastic modulus and the strength of hydrated silicate glass decreased with increasing water content, while McMillan et al [6] reported that the bending strength of the soda-lime silica glass with a small amount of water (below 780 ppm) was not influenced by the water content. So far, no research has been reported on details of the effect of the water in glass on the strength, especially on fatigue phenomenon.In this study, the stress rate dependency of the mechanical strength and the elastic modulus of the sodium silicate glass with high water content were investigated.

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“…However, since P n the net horsepower is about 0.8 P where P is the gross power, then 0.6 appears in Equation (52).…”

Section: **Tousementioning

confidence: 99%