In order to study the mechanical properties and failure mechanism of unloading damaged surrounding rock

RMT-150 rock mechanics test system was selected to carry out tests on triaxial rock in loading-unloading process to prepare damaged rock. Combined with AEwin acoustic emission system

the uniaxial reloading test was conducted on damaged limestone

the relationship curve of stress-time-energy accumulation was tested

and the macroscopic failure characteristics of the rock were analyzed. Experimental results show that with the increase of unloading points

the damage degree and failure form of the damaged limestone were changed obviously. The failure form of the limestone transformed from brittle failure to ductile failure

and the phenomenon of expansion was less and less obvious. In the process of uniaxial loading

the variation in the cumulative value of the acoustic emission energy of the damaged rock with peak strength lower than 70% tended to be the same

which can be divided into three stages: stable stage

stable growth stage

and secondary stable stage. The distribution mode of micro-cracks in rock had an obvious influence on its macro-failure characteristics

and the micro-mechanical response of rock determined its macro-mechanical failure characteristics.