• Increasing impact numbers cause crack closure, damage, and peak stresses to first rise then decline, while higher confining pressure monotonically increases these thresholds.
• Crack damage stresses determined by crack volume strain and acoustic emission methods were compared, revealing consistency and informing method selection.
• An improved acoustic emission method, using rise time amplitude and average frequency, accurately identifies crack damage stress and tracks microcrack evolution.
• Shear crack proportions first decrease then increase with impact number and decrease with confining pressure; tensile cracks show the opposite trend, aiding rock stability assessment.