Experimental Study on Pressure Relief Mechanism of Variable-Diameter Borehole and Energy Evolution Characteristics of the Surrounding Rock

Conventional borehole pressure relief can meet the requirements for preventing rock bursts, but it also easily destroy roadway, resulting in system support failure. Taking coal-like samples with boreholes as research object, effects of same-diameter and variable-diameter are compared analyzed by a uniaxial compression test. The joint mechanism drilling hole is discussed. experimental results show that stress–strain curve sample occurred phenomenon pre-peak stress drop post-peak plateau, which indicates enhance plastic characteristics samples. size dramatically influences variation various indexes. evolution law AE counting verified abovementioned law. Variable-diameter plasticity samples, weaken brittleness reduce impact tendency. Under maximum same, effect more significant. obtained this paper provide new theoretical basis technical guidance roadway support.