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Thermal shock assisted percussive drilling: A numerical study on the single-bit axisymmetric case

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Yksityiskohdat

AlkuperäiskieliEnglanti
Artikkeli104365
Sivumäärä18
JulkaisuInternational Journal of Rock Mechanics and Mining Sciences
Vuosikerta132
DOI - pysyväislinkit
TilaJulkaistu - 2020
OKM-julkaisutyyppiA1 Alkuperäisartikkeli

Tiivistelmä

This paper presents a numerical study on thermal shock assisted percussive drilling. For this end, a finite element based numerical approach for solving the governing thermo-mechanical problem explicitly in time is presented.
Rock fracture is described in the continuum sense by a damage-viscoplasticity model with separate damage variables for tensile and compressive failure types. In the numerical simulations, an axisymmetric numerical rock is dynamically indented with a spherical tool in cases of intact and heat shocked heterogeneous rocks. In realistic simulations with an initial borehole, the heat shock treatment of rock enhances the mechanical breakage, increasing especially the tensile damaging, in unconfined and confined conditions with and without down-the-
hole pressure. However, according to the simulations, down-the-hole pressure effectively prevents the thermal spallation phenomenon crucial for thermal jet drilling.

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