Study on the influence of high geothermal in the middle of a tunnel on the pressure wave value and the mechanism underlying propagation

Mechanisms underlying propagation and variation of pressure waves (PWs) in high geothermal tunnels are intricate and multifaceted, making them difficult to study and analyze using existing methods. In this work, the mechanisms underlying the propagation and variation of PWs in high geothermal tunnels are investigated via moving model experiments, numerical simulations, and a new PW model method. These findings confirm that the improved PW simulation method can effectively model the propagation patterns and velocities of PWs in high geothermal tunnels. The improved PW method is used to conduct an in-depth analysis of the phenomenon, as observed in studies of geothermal zone distribution, where the amplitude of the expansion wave increases when geothermal conditions are present at the front section of the tunnel. When geothermal zone is present in the front part of the tunnel, the intensity of the PW decreases to a certain extent when it passes through the geothermal area. Notably, upon reentering the normal temperature zone, the intensity of the PW increases and progressively builds up in the middle and rear sections of the tunnel. The underlying mechanism driving the amplification of the expansion wave amplitude has been elucidated. This research explores the rise in PWs caused by the presence of a front section within the tunnel, offering a fresh perspective on the mechanisms behind PW variations in high geothermal tunnels.