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Journal of Mining Sciences

2014 year, number 2

Dynamic Microplasticity Phenomenon in Rocks during P-Wave Propagation

E. I. MASHINSKII
Trofimuk Institute of Petroleum Geology and Geophysics Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090 Russia
Keywords: local inelasticity, dynamic microplasticity, time lag and deformations, inelastic seismic parameters, amplitude dependence of wave velocities and attenuation

Abstract

The article describes effects of local microplastic inelasticity in loam during propagation of P-wave with a frequency of 240–1000 Hz between two shallow wells, one holding piezoelectric pulse emitter and the other containing piezoelectric pulse receiver. Seismic record displays microplasticity phenomenon as the step-wise change of signal amplitude with time and the flat sections in the curve from microsecond to dozens microseconds long. The flats create short-terms breaks of the process-the time lags that depend on the signal amplitude. As a result, the first arrival time of the wave is changed, and the wave is transformed. It is presumable that microplasticity is conditioned by stress concentration at damages. The research findings are of use to solving applied problems in mining engineering and seismology.