Temperature induced pore fluid pressurization in geomaterials

TL;DR

This paper presents a theoretical and experimental analysis of how temperature changes induce pore fluid pressurization in saturated porous materials, emphasizing the effects of thermal expansion discrepancies, stress-dependent compressibility, and drainage system corrections.

Contribution

It introduces a correction method for undrained thermo-poro-elastic measurements considering drainage system effects and provides experimental validation on granular rock.

Findings

Thermal pressurization depends on fluid and solid thermal expansion differences.

A correction method improves measurement accuracy by accounting for drainage system volume.

Porosity and drainage system ratio significantly influence measurement errors.

Abstract

The theoretical basis of the thermal response of the fluid-saturated porous materials in undrained condition is presented. It has been demonstrated that the thermal pressurization phenomenon is controlled by the discrepancy between the thermal expansion of the pore fluid and of the solid phase, the stress-dependency of the compressibility and the non-elastic volume changes of the porous material. For evaluation of the undrained thermo-poro-elastic properties of saturated porous materials in conventional triaxial cells, it is important to take into account the effect of the dead volume of the drainage system. A simple correction method is presented to correct the measured pore pressure change and also the measured volumetric strain during an undrained heating test. It is shown that the porosity of the tested material, its drained compressibility and the ratio of the volume of the drainage system to the one of the tested sample, are the key parameters which influence the most the error induced on the measurements by the drainage system. An example of the experimental evaluation of undrained thermoelastic parameters is presented for an undrained heating test performed on a fluid-saturated granular rock.