Model Experimental Study on Blasting Vibration Response of Tunnel Surrounding Rock under Different in Situ Stresses

Studying the propagation characteristics of blasting seismic waves in surrounding rock under different in situ stresses forms the basic framework for discussing the damage and failure laws of tunnel surrounding rock caused by deep engineering blasting vibration. To study the propagation law of blasting seismic waves under different in situ stresses, an underground engineering model test system is used to simulate tunnel blasting excavation with a nonexplosive electric spark initiation device. The vibration acceleration and strain of the surrounding rock during excavation are collected in real time. Based on the test data system, the blasting vibration response characteristics of tunnel surrounding rock under different in situ stresses are discussed. According to the results of experimental studies, the peak values of radial and axial acceleration show nonlinear attenuation with an increase in distance under different in situ stresses. With an increase in in situ stress, the attenuation rate of the peak value of radial acceleration decreases, while that of axial acceleration increases. Moreover, the peak values of acceleration and strain measured at the same point near the seismic source under different in situ stresses remain unchanged, whereas those measured at the same point far away from the seismic source gradually decrease. Moreover, the attenuation rate at the stage of low in situ stress is greater than that at the stage of high in situ stress. The farther away from the seismic source, the greater the influence of in situ stress on peak acceleration and peak strain. The research results play an important guiding role in the development of deep tunnel blasting theory and safe construction.