Thermal Effects on the Drilling Performance of a Limestone: Relationships with Physical and Mechanical Properties

This work evaluates the effect of high temperatures and cooling methods on drillability Prada limestone. Samples from boreholes drilled during design stage Tres Ponts Tunnel in Catalan south Pyrenean zone (Spain) were subjected to 105, 200, 300, 400, 600 °C, then cooled at a slow rate or by quenching. Sievers’ J-value (SJ) brittleness (S20) determined thermally treated samples, drilling index (DRI) was calculated for each temperature. The results show that thermal treatment implied sustained increase rock up 40% °C change category (from medium high). At SJ S20 tripled doubled, respectively, initial values obtained intact rock. inconclusive about influence method performance limestone tested range temperatures. substantial improvement observed when heated, measured terms DRI, could help development novel thermally-assisted mechanical excavation methods. Additionally, strong correlations between variables (i.e., S20) physical P- S-wave velocities, uniaxial compression strength, elastic modulus, Poisson’s ratio) are proposed. Correlations will make preliminary predictions based properties such as strength ultrasound wave velocities.