Experimental　studies　indicated　that　most　rocks　exhibit　distinct　elastic　moduli　under　compressive　and　tensile　loading,　leading　to　intricate　stress　conditions　in　rock　mass　under　thermal–mechanical　coupling.　It　is　an　urgent　demand　for　advanced　numerical　methods　that　can　simultaneously　consider　the　bi-modular　elasticity　of　rock,　thermal–mechanical　coupling　effects,　and　thermal　cracking　behaviors　to　improve　understanding　of　geological　science.　The　Balanced　Interface　Method　(BIM),　a　novel　bi-modular　elastic　algorithm　is　proposed　in　Particle　Flow　Code　to　investigate　the　thermal–mechanical　behavior　of　bi-modular　elastic　materials.　Firstly,　this　study　introduces　the　calculation　principle　of　BIM　and　presents　the　calibration　procedure　for　bi-modular　elastic　materials,　which　is　further　validated　through　two　case　exercises.　Subsequently,　the　thermal–mechanical　coupling　algorithm　is　improved　by　utilizing　the　Flat-Joint　Model　(FJM),　and　a　correction　method　for　the　position　of　the　compression-tension　interface　based　on　BIM　for　the　thermal–mechanical　coupling　process　is　introduced,　which　is　then　verified　by　a　comprehensive　transient　heat　conduction　case　with　different　elastic　assumptions.　Lastly,　a　cracking　example　induced　by　thermal–mechanical　coupling　is　simulated.　The　numerical　results　demonstrate　consistency　with　previous　studies　and　reveal　a　significant　improvement　in　the　thermal　cracking　behavior　of　rock,　proving　the　developed　algorithm＇s　necessity　in　investigating　the　coupled　thermal–mechanical　problem.　©　2024　Elsevier　Ltd