Mechanical-acoustic-optical response properties in uniaxial compression failure of rock masses with different dissolution degrees

To reveal the effects of dissolution cavities on the mechanical properties and failure mechanisms of surrounding rock, uniaxial compression tests were conducted on rock-like specimens with dissolution degrees of 0%, 5%, 10%, 15%, and 20%. A mechanical-acoustic-optical integrated system combining acoustic emission (AE) and digital image correlation (DIC) was used to characterize mechanical response, AE activity, strain field evolution, and failure behavior. The results indicate that with increasing dissolution degree, compressive strength, elastic modulus, peak axial strain, and deformation modulus decreased by 36.45%, 27.01%, 17.25%, and 41.28%, respectively. Post-peak failure gradually changed from rapid coalescence of a single dominant crack to progressive failure controlled by multiple defects. AE activity shifted from concentrated release near peak strength to continuous release throughout loading, accompanied by earlier crack initiation and an expanded pre-peak damage interval. Crack activity evolved from small scale microcracking to the propagation and coalescence of larger scale cracks. Combined AE and DIC results further showed a transition from axial tensile splitting failure to progressive mixed tensile-shear failure with multiple shear strain concentration zones and coordinated crack coalescence. These findings provide experimental evidence for stability assessment and disaster mitigation of dissolution voided surrounding rock in karst underground engineering.