Thermal Damage Impact on Negative Poisson's Ratio of Granite Under Brazilian Tensile Loading

This study investigates the effects of thermal damage on the tensile behavior of granite during Brazilian splitting tests, focusing on the negative Poisson's ratio (NPR) effect. Using digital image correlation and acoustic emission techniques, the research reveals that increasing thermal damage from 25°C to 800°C reduces granite tensile strength by up to 85.7% and induces a brittle-to-ductile transition. The NPR effect emerges, intensifies, and subsequently disappears as temperature increases, significantly altering stress distribution and deformation patterns. Local contraction zones created by the NPR effect can lead to overestimation of tensile strength in thermally damaged rock. Acoustic emission monitoring demonstrates a strong correlation between the NPR effect and microcrack development. These findings advance the understanding of rock mechanical behavior under thermal damage and provide practical insights for tensile strength evaluation in high-temperature geological settings, such as deep underground energy development and nuclear waste disposal.