To explore rock strength characteristics and fracture mechanisms under different cooling methods

limestone subjected to high temperature was naturally cooled or water-cooled. Brazilian splitting tests and acoustic emission measurements were performed on the limestone samples after high-temperature treatment

tensile strength under different cooling methods was measured

and the tensile and shear crack evolution during failure was analyzed using a K-Means algorithm. A numerical model of limestone was constructed by using PFC

and the influence of temperature and cooling mode on the tensile strength

crack evolution

displacement field and force chain of limestone was analyzed. The results show that: (1) The tensile strength of limestone decreases with the increase of temperature

and the strength of limestone cooled by water is lower than that under natural cooling conditions. Compared with the limestone without high temperature treatment

the tensile strength of naturally cooled limestone at 200−600°C decreases by 21.8%

62.8% and 77.3%

and the tensile strength of limestone cooled by water decreases by 54.5%

65.3% and 79.2%. (2) As temperature increases

pre-peak acoustic emission events increase and internal damage accumulates; tensile cracks are observed throughout loading

while shear cracks occur mainly near the peak and post-peak stages. (3) With increasing temperature

crack complexity increases; under water cooling

the main crack arises from numerous cracks

event magnitudes become more frequent

the displacement field becomes more irregular

and the stability of force-chain networks decreases.