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Water has a significant influence on rock mechanical and fracture behavior in geologic engineering. This study investigates the water weakening effects on mechanical properties, as well as the microscopic failure, of hard marble. Uniaxial compression tests, with the aid of a PCI-2 monitoring system to record acoustic emission (AE) data during the entire loading application, are carried out on dry and saturated rock specimens. The results of this study show that, as marble is saturated, its uniaxial compressive strength and elastic modulus both decrease, while the Poisson's ratio increases. Compared with the dry marble, AE events of saturated marble are reduced, and its b-value is inclined to decrease intensively at the moment when stress drops for the first time. Using a new waveform-based AE analysis approach, two dominant frequency bands of AE waveforms are revealed, regardless of the effects of water. The percentage of low dominant frequency waveforms significantly increases and these waveforms become dominant, owing to the existence of water; this mainly results from pore water pressure. [ABSTRACT FROM AUTHOR]