Similarity simulation study on coal mine goaf temperature field dynamic evolution influenced by initial stop-mining temperature

Unsealed goafs after stop-mining (UGSM) are formed when operations halt temporarily without subsequent sealing. These areas present significantly higher risks of coal spontaneous combustion compared to the normal mining phase. Current similarity simulations often fail to replicate the complex initial stop-mining temperature (ISMT), leading to an inaccurate understanding of subsequent combustion evolution. To address this deficiency, this study introduces a novel method. First, the ISMT is predicted under different conditions using self-developed numerical software. Then, the field is replicated in a physical similarity model using temperature-controllable copper heating tapes (TCCH). Simulations using two advancing speed (2 m/d and 4 m/d) were conducted over 48 h and 120 h to analyze how ISMT impacts temperature evolution in the goaf, with experimental data validating numerical software. Key findings: (1) Numerical results align well with experimental data, verifying self-developed simulation software reliability; (2) After stop-mining, high-temperature zones concentrate on intake side and migrate toward working face to access more oxygen; (3) Higher ISMT intensifies coal oxidation and expand high-temperature zones, while accelerating the migration rate of these high-temperature points toward the working face. This study provides a more accurate method for setting initial conditions in similarity simulations. Furthermore, the validated software offers a reliable tool for early warning and prevention of goaf fires during stop-mining, which is crucial for mine safety.