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

Abstract

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

Study on Dynamic Loading Characteristics of Rock Containing Holes

“…Similarly, Lin et al [27] examined the impact of random and structured hole distributions on crack initiation, coalescence, and the failure patterns of rock materials, subsequently suggesting a criterion based on hole distribution. Furthermore, Li et al [28] assessed the efficacy of boreholes with varying diameters compared to those with uniform diameters, revealing that boreholes with fluctuating diameters significantly enhance pressure relief more effectively than uniform diameter boreholes with the same maximum diameter.…”

Numerical Simulation Analysis of Acoustic Emission Characteristics during the Drilling Pressure Relief Process in Coal Seams under Different Influencing Factors

“…Zhang et al [13] studied the shear failure characteristics caused by compressive stress concentration around non-circular drilling. Li et al [14] investigated the energy, stress, and impact tendency of the pressure relief principle of drilling. The method of using electromagnetic wave CT detection technology to test the pressure relief effect of drilling was proposed and verified.…”