Mesomechanics of shear resistance along a filled crack

Kocharyan, G. G.; Марков, В. К.; Остапчук, А. А.; Павлов, Д. В.

doi:10.1134/s1029959914020040

Cited by 30 publications

(10 citation statements)

References 10 publications

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“…This facilitates formation of a larger number of load bearing chains, and consequently the stress jump amplitude increases when they are dynamically bro ken. This is directly demonstrated in the experiments with round and angular particles [8,9].…”

Section: The Influence Of Viscosity Of Thin Fluid Films On the Frictimentioning

confidence: 72%

The influence of viscosity of thin fluid films on the frictional interaction mechanism of rock blocks

Kocharyan

Остапчук

2015

Dokl. Earth Sc.

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In the past few years, as a result of accomplishment of a number of international drilling projects in frac ture zones, new important results have been published about the structure of fractures of mega earthquakes and the properties of the geomaterials that make them up [1]. Especially interesting data were obtained as a result of sampling in the Nankai Trough [2, 3] and the Japan Trench including sampling in the fracture of the Tohuku mega earthquake fracture of March 11, 2011, with moment amplitude М w = 9.0 [4,5]. We focus attention on the fact that the frictional properties of the materials taken from various fractures are signifi cantly different [2][3][4]. This leads to the formation of different deformation regimes under the conditions of a close stressed state: slow earthquakes [2, 3], tsunami genic earthquakes of the Tohuku type [4], and "typi cal" events [2]. Some of the authors think that the dif ferent frictional behaviors may be related to the differ ent composition of clayey materials, which compose from 37 to 85% of the ground material sampled from the central parts of the fracture zones [2,4]. Such a high concentration of clay is characteristic of the upper part of the fracture located within the accretion prism and near it. As the depth increases, the concen tration of clay decreases and the content of quartz increases, which leads to the possibility of instability [3]. Nevertheless, the material at sufficiently shallow depths in the main part of the fracture invariably con tains minerals such as smectite, kaolinite, and others. Colloidal films formed by the clayey minerals have clearly manifested viscous properties and even being present in small quantities can have a strong influence on the frictional characteristics of the fracture.In this paper we present the results of laboratory experiments in which we found a new effect of the rad ical variation in the shear deformation of a crack after passing a specific viscosity limit of the thin fluid films that wet the particle surfaces of the filling material.In our experiments a granite block with a size of 8 × 8 × 3 cm was located on an immovable granite basement. The contact between the rough surfaces was filled with a layer of quartz sand 2.5 mm thick with a mean size of the grains d = 0.2-0.3 mm. The mean depth of the inhomogeneities of the rough surface was notably greater than the grain size; it was equal to 0.5-0.8 mm. A normally directed load was applied to a mobile block using a special device that excluded the appearance of shear stresses at its upper surface. The applied stress σ n ranged between 50 and 150 kPa. The shear load was applied to the block using a spring ele ment with rigidness K = 10-40 N/mm. The rate of the spring deformation was constant and equal to u s = 20 µm/s. The shear stress applied to the upper block was measured with a force sensor SMS/5kN with an accuracy to 1 N, while the relative displacement of the blocks was recorded using laser sensors ILD2220-10 (G) in the frequency band 0-5 kHz with an accuracy to 0.1 µm.I...

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Section: The Influence Of Viscosity Of Thin Fluid Films On the Frictimentioning

confidence: 72%

The influence of viscosity of thin fluid films on the frictional interaction mechanism of rock blocks

Kocharyan

Остапчук

2015

Dokl. Earth Sc.

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“…It was noted in the experiments that a significant factor in the activation of geodynamic events is the direction of arrival of the deformation wave from the earthquake to the controlled rock mass, which requires further research. 4. The experiments established that the anomalous behavior of the deformation field in the low-frequency region in the working band is often up to 50 MHz for 1.5 days before the rock burst.…”

Section: Resultsmentioning

confidence: 96%

“…As researchers [4][5][6] have shown, deformation-wave processes in the Earth's crust are a trigger mechanism for various high-energy seismic events (earthquakes, rock bumps, etc.). At the same time, they can be the harbingers of these events.…”

Section: Introductionmentioning

confidence: 99%

Deformation waves from distant earthquakes as a trigger mechanism for activating geodynamic processes in rock mass

et al. 2020

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The results of experimental studies with a laser strainmeter and a multichannel automated geoacoustic rock pressure control system “PROGNOZ ADS” aimed at identifying the nature of the effect of deformation waves from distant earthquakes on the geodynamic activity of the monitored rock mass are presented. The quantitative and energy characteristics of geoacoustic emission before and after the arrival of deformation waves in the controlled rock mass are analyzed. The analysis performed indicates a trigger mechanism of the influence of a distant earthquake on the geodynamic activity of the rock mass. It is noted that the direction of arrival of the deformation wave is an essential factor in the intensification of geodynamic activity in the rock mass. The experiments also revealed the characteristics of rock burst precursors when registering deformation waves in the low-frequency range.

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“…The experiments used a "slip" type device that is in detail described, e.g., in [16]. A marble block 8×8×3 cm 3 was placed on an immovable granite support.…”

Section: Implementation Of Different-type Shearingmentioning

confidence: 99%

“…The materials featured an average grain size 0 δ and distribution n. The latter parameter is an exponent of power in the Rosin-Rammler distribution [17]. The structural and physico-mechanical characteristics of the filling materials can be found in [16].…”

Section: Implementation Of Different-type Shearingmentioning

confidence: 99%

Acoustic emission during different-type inter-block movements

Kocharyan

Остапчук

2015

J Min Sci

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The article reports the lab experimentation on seismic/acoustic emission during different-type inter-block movements of rock mass. The fact that co-seismic displacement under induced earthquakes occurs along the existing interfaces is the basis for relatively simple tests on a slip-model plant. Using different materials as fracture fillers allowed modeling entire range of probable deformation modes. The deformation modes are conditionally grouped as creep or steady-state slip, unsteady-state slip and regular discontinuous slip or stick-slip. The authors show that statistics of acoustic emission during slip is described using the Gutenberg-Richter law. The strongest "representative" events under shearing occur quasiregularly, with probability much higher than follows from G-R law. The functional relation is found between the acoustic emission energy and the shear velocity.

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Mesomechanics of shear resistance along a filled crack

Cited by 30 publications

References 10 publications

The influence of viscosity of thin fluid films on the frictional interaction mechanism of rock blocks

The influence of viscosity of thin fluid films on the frictional interaction mechanism of rock blocks

Deformation waves from distant earthquakes as a trigger mechanism for activating geodynamic processes in rock mass

Acoustic emission during different-type inter-block movements

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