The mechanical properties of high-temperature rocks

after being cooled by various methods

significantly influence the safety of deep earth geotechnical engineering. The study primarily investigated medium-weathered granite porphyry. Uniaxial compression and cyclic dynamic impact tests were performed on specimens cooled naturally and via water immersion at 400 ℃. The aim was to compare and analyze the change in the mechanical properties of granite. Utilizing the Logistic distribution law

loading damage variables and thermal cycling damage variables were incorporated to develop a statistical damage constitutive model for granite. The corresponding parameters were determined

and the applicability and reasonableness of the model were verified. The results reveal that during uniaxial compression testing

the internal microcracks in granite expand and coalesce into macroscopic cracks as the number of thermal cycles increases. Furthermore

the mass of the rock samples and longitudinal wave velocity decrease

while the elastic deformation phase in the static stress-strain curve shortens

indicating a distinct unstable damage stage. The rate of deterioration of rock strength can be significantly affected by the cooling method

but the final static compressive strength of granite is not significantly affected. Under an air pressure impact of 0.30 MPa

the dynamic compressive strength of naturally cooled granite initially increases and then decreases with increasing impact cycles. The initial impact enhances the compressive strength of naturally cooled granite. However

when thermal cycling exceeds three cycles

granite's resistance to cyclic impacts diminishes. The dynamic damage model

formulated using the Logistic distribution

exhibits good alignment with the experimental curve. The model parameters are readily obtainable

possessing a clear physical interpretation and practical applicability. This research offers valuable references for the construction

repair

and stability analysis of rock masses in variable temperature environments.