Wyniki wyszukiwania - BazTech

1

From statistics of avalanches to microscopic dynamics parameters in a toy model of earthquakes

Białecki M.

Acta Geophysica

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2013

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Vol. 61, no. 6

1677--1689

EN

A toy model of earthquakes - Random Domino Automaton - is investigated in its finite version. A procedure of reconstruction of intrinsic dynamical parameters of the model from produced statistics of avalanches is presented. Examples of exponential, inverse-power and M-shape distributions of avalanches illustrate remarkable flexibility of the model as well as the efficiency of proposed reconstruction procedure.

2

Crackling noise in a discrete element model of single crack propagation

Timár G., Kun F.

Computer Methods in Materials Science

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2011

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Vol. 11, No. 2

309-314

EN

We study the crackling noise emerging during single crack propagation obtained by discrete element modelling (DEM) in a specimen under three-point bending conditions. Analyzing temporal and spatial correlations of local breakings we show that the crack proceeds in bursts, which are characterized by power law distributions of their size and of the waiting times between consecutive events. We obtain a generic scaling form which describes crackling noise in materials with different degrees of heterogeneity. The results are in a good agreement with acoustic emission measurements in three-point bending experiments.

PL

W pracy badano odgłos pękania występujący podczas propagacji pojedynczego pęknięcia w proce poddawanej trzypunktowemu zginaniu, symulowanemu za pomocą metody elementów dyskretnych (ang. Discrete element method - DEM). Analiza czasowych i przestrzennych zależności lokalnego pękania wykazała, że pęknięcie postępuje przez rozdzielenie, co charakteryzuje się prawem potęgowym opisującym rozmiar szczelin oraz czasy przerw między kolejnymi etapami pękania. Opracowano ogólną postać skalowania, które opisuje odgłos pękania w materiałach o różnym stopniu niejednorodności. Uzyskane wyniki są zgodne z pomiarami emisji akustycznej w próbie trzypunktowego zginania.

3

Dendrochronological records of debris flow and avalanche activity in a mid-mountain forest zone (Eastern Sudetes - Central Europe)

Malik I., Owczarek P.

Geochronometria

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2009

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Vol. 34

57-66

EN

Dendrochronological methods were used to determine the frequency of debris flow/avalanche events in a forest zone. A debris flow and avalanche track located in the Eastern Sudetes Mountains (Central Europe) was analysed. The length of the youngest debris flow/avalanche track is about 750 m. Three distinct sections of the debris flow can be identified along the longitudinal section: niche, gully and tongue. The dendrochronological study shows that trees started growing on the margins of the debris flow between 1908 and 1963. Hence, debris flow and/or avalanche events occurred on this slope at the turn of the 19th and 20th centuries. All trees collected from the tongue started growing between 1935 and 1964. However, a large debris flow event took place several years before, most probably during an extraordinary rainfall in June 1921. Following this event, several relatively large debris flows have occurred during the growing season, the strongest dendrochronologically confirmed events occurring in 1968, 1971-1972, 1991, 1997 and probably in 1977. Spring debris flow events induced by snow melt and/or avalanches have occurred in 1994 and 2004. The results suggest that with favourable geological conditions, debris flows can occur very frequently within entirely forested slopes.