The hardness and thickness of coal seam play a great role in the vertical distribution of stress in coal and the occurrence of rock bunt under the condition of hard roof and hard floor.

• 在“两硬”条件下，煤层厚度与硬度的变化对煤体中的应力分布有着很大的影响，从而对煤岩体系统中冲击矿压的发生有着很大的影响。