Fracture Mechanism of the Rock Under the Action of Shock Waves
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ture Mechanism of the Rock Under the Action of Shock Waves I. P. Shcherbakova, V. I. Vettegrena, b, *, and R. I. Mamalimova, b aIoffe
bSchmidt
Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, 123242 Russia *e-mail: [email protected] Received February 21, 2019; revised April 20, 2020; accepted April 23, 2020
Abstract—Fracture mechanism and dynamics is studied with a time resolution of 2 ns in the quartz, granite, gabbro-diabase, and calcite samples in a shock wave field. It is found out that jets of positively charged ions are ejected from the shock-loaded surface of minerals. The structure of the surface layer of these rocks after loading by shock waves is studied by the infrared, Raman, and photoluminescent spectroscopy. It is established that in the surface layers of quartz and granites, diaplectic glasses are formed, whereas in the surface layers of calcite—the high pressure phase—calcite III is produced. Keywords: shock waves, fracture mechanism and fracture dynamics, granites, calcite DOI: 10.1134/S1069351320050092
INTRODUCTION By now, numerous attempts have been made to study the mechanism of destruction and deformation of rocks under the influence of shock waves (Adushkin and Spivak, 1993; Bykova et al., 1987; Kanel et al., 2007; Fortov, 2007; Adushkin and Soloviev 1996; Galvez, 2011; Kanel et al., 2004; O’Keefe and Thiel, 1991). The main difficulty encountered by the authors of these works is that the speed of shock waves is greater than the rate of crack growth (Morozov and Savenkov, 2013; Regel et al., 1974; Petrov et al., 1983), so during the activity of the shock wave, cracks do not have time to form and grow. Previously, there was no experimental technique that allowed us to find out what the mechanism of destruction during the activity of a shock wave was. It was estimated mainly by the results of the study of fracture surfaces after the impact of shock waves. Several years ago we built devices that allow us to study the mechanism of destruction some minerals with a time resolution of 2 ns. This made it possible to study experimentally the dynamics of rock destruction directly during the shock wave activity. Most of the works describing the results of studies of destruction in the shock wave field were published in the journals “Physics of the Solid State” and “Technical Physics,” which are not very popular among geophysicists. Therefore, below there is a brief overview of the work performed by us in recent years, in which we studied the mechanism and dynamics of destruction of quartz, granites, gabbro-diabase and marble. Before continuing with their presentation, we should note that studies of the mechanism of destruc-
tion of other solids (metals, crystals, polymers and composites) with a time resolution of 2 ns have not been conducted until now. Therefore, the question of the extent to which the results described below can be valid for other solids remains open. The article consists of three
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