Pore Structure Evolution and Failure Mechanism of Limestone in the Taiyuan Formation of the Ordos Basin under High Temperature.

The study on the destruction of the limestone microstructure after high-temperature treatment has a significant value in the airtightness and safety of underground high-temperature geotechnical engineering. In order to truly simulate the influence of the underground high-temperature environment on limestone, taking seven groups of limestones of the Taiyuan Formation in the Ordos Basin as examples, we carried out a high-temperature (25-1200 °C) heating experiment of limestone in an argon atmosphere. The pore structure of limestone after the high temperature is studied based on scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), porosity, and permeability, and the change in the fractal dimension of the limestone pore structure was discussed based on the thermodynamic fractal theory, combined with X-ray diffraction (XRD) and thermogravimetry differential scanning calorimetry (TG-DSC), the variation of mineral composition with temperature is characterized, and the evolution mechanism of the limestone microstructure under high temperature is discussed.