Experimental study on the mechanism of rockburst in tunnel construction by drilling and blasting construction in high ground stress stratum

In order to explore the mechanism of rockburst in tunnels constructed by drilling and blasting method in high ground stress strata, this study reformed the physical model test system of rockburst in deep tunnels and the high-pressure gas explosion excavation system, and successfully reproduced the process of rockburst disaster in drilling and blasting construction. Based on the existing research results and preliminary tests, a composite material with similar brittleness and rock burst tendency index to the granite on site was developed, and a cubic rock burst model of 500 × 500 × 500 mm³ was poured. The test results show that in the gas explosion excavation, the air pressure impact causes the test block to be destroyed instantaneously, the small fragments splash and the explosion sound is significant, indicating that the instantaneous release of gas can cause material damage and simulate the dynamic characteristics of the blasting process. From a macro point of view, rockburst originates from the stress adjustment of surrounding rock of the cavern and the energy transfer and dissipation process inside the rock mass. The residual energy is released in the form of dynamic energy and dissipated by dynamic mechanism. Microscopically, the material is compressed and destroyed in a small range of gas explosion tube pores, and the surrounding rock debris is mainly tensile and shear failures. The shear and tensile stress make the tunnel damage debris complex. The test results show that the stress at the measuring point 3 cm away from the cavern after excavation drops sharply at T = 11915s, with a decrease of 56.69%. At 30.50 cm from the cavern, the strain at the measuring point 3 cm from the cavern increases. The sharp rise of acoustic emission count and energy indicates that the rock burst phenomenon is sudden. The test method of this study effectively simulates the rock burst of tunnel constructed by high ground stress drilling and blasting method, which provides important experimental basis and data support for theoretical research and engineering practice of rock burst.