TUTCRIS Research Portal

TY - JOUR

T1 - Thermal shock assisted percussive drilling

T2 - A numerical study on the single-bit axisymmetric case

AU - Saksala, Timo

PY - 2020

Y1 - 2020

N2 - 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.

AB - 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.

U2 - 10.1016/j.ijrmms.2020.104365

DO - 10.1016/j.ijrmms.2020.104365

M3 - Article

VL - 132

JO - International Journal of Rock Mechanics and Mining Sciences

JF - International Journal of Rock Mechanics and Mining Sciences

SN - 1365-1609

M1 - 104365

ER -