Experimental study of the permeability and poromechanical properties of thermally damaged granite

Abstract

Two objectives are targeted with this experimental study carried out on a granite heated up to 600 °C. The first one is to evaluate the coupled effects, on permeability and poromechanical properties, of the thermal treatment followed by three kinds of cooling (slow process in the oven or in the air and quick process in cold water). The second objective was to analyse the efficiency of the experimental procedure carried out to make the measurements, i.e. the use of inert gas or water to control the pore pressure. The use of gas clearly leads to more accurate observations than with water. It is especially true on the effects of confining pressure on permeability. A micro-cracking process goes along with the heating and is amplified by the thermal shock. This leads to high increase in permeability, which becomes more and more sensitive to the confining pressure. This is confirmed by the decrease in the drained bulk modulus K_b, in the expansion coefficient H and the increase in the Biot’s coefficient.

Keywords:

• Granite
• permeability
• poromechanical properties
• thermal treatment

Disclosure statement

No potential conflict of interest was reported by the authors.