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Stress evolution of rock breakages by a disc cutter assisted by pre-cuts

Liu Jie, Chen Wei, Liu Taoying, Peng Di

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e115, 2023

EN

To study the rock breakage mechanism by constant cross-section cutters assisted by pre-cuts, the present study first performed small-scaled linear cutting tests on sandstone specimens containing pre-cuts. The laboratory tests indicate that the sufficiently large penetration, causing successful internal and surface crack incisions, is essential for large chip formation. In addition, the small pre-cut depth may fail to form large chips. The numerical results agree well with laboratory tests in fracture patterns. More importantly, the numerical analysis indicates that the increases in rolling force frequently result in stress concentrations. When the stresses concentrate to critical values, fracture propagation occurs. The fracture propagation causes stress dissipation and the decrease in rolling force. Thus, the relation between cutting load fluctuations and crack propagation is revealed. Moreover, the influence of penetration on crack propagation is analyzed. By analyzing the stress fields at typical peak points of the rolling force, the crack propagation direction is predicted, and the influence of pre-cut depth on fracture propagation is studied.

2

Dislocation dynamics and related electromagnetic excitation

Teisseyre R.

Acta Geophysica Polonica

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2001

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Vol. 49, nr 1

55-73

EN

Theory of stress and dislocation evolution is based on the equation of motion for the self-stresses on the slip-fault plane; this equation is supplemented with the source/sink function entering in a similar way as the body forces in the equation of motion for displacements. We present the effects of dislocation dynamics on generation of electric current and electromagnetic field emission.

3

Stress and dislocation field evolution and prediction problems of numerically simulated events

Teisseyre R., Yamashita T.

Acta Geophysica Polonica

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2000

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Vol. 48, nr 1

43-56

EN

Numerical simulations of the dislocation density evolution exhibit some perturbations which may be identified as seismic events. The influences of tidal stresses and random disturbances related to the material heterogeneities are analyzed. In relation to this analysis some problems of earthquake prediction and earthquake precursors are discussed. Occurrences of seismic events are very sensitive to small disturbances, while the great disturbances in tidal influence or in material properties cause the disappearance of the events.

4

Thermodynamics of line defects and transient electric current: electromagnetic field generation in earthquake preparation zone

Nagahama H., Teisseyre R.

Acta Geophysica Polonica

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1998

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Vol. 46, nr 1

35-54

EN

In thermal equilibrium the electrical neutrality of the charge dislocation is assured by a cloud of oppositely charged point defects around it. Here, from the view point of thermodynamics of line vacancies, we propose a possibility of constructing a model of transient electric current generation in an earthquake source zone which combines polarization processes and motion of charged dislocations under the influence of evolving field of stresses. This transient electric current differs essentially from the piezo-electric current in which the electric field is proportional to the stress itself. Then we review briefly the elements of stress evolution theory. Some examples of the stress evolution pattern with the electromagnetic field radiation are shown.