Model test study on the dynamic response of surrounding rock in deep buried tunnel under explosive plane wave

Abstract

In order to clarify the dynamic failure mechanism in deep buried tunnels, a modeling test of the dynamic response of the surrounding rock in deep buried tunnels under the action of explosion plane wave was carried out by using the geotechnical multi-functional test device. Based on Froude’s similarity theory, a model with dimensions of 1600 × 1300 × 400 mm was constructed using low-strength cement mortar. Using the detonating fuse as the explosive source, the explosion tests were conducted with an equivalent TNT amount of 52.8 g and 105.6 g, respectively. According to the measured data, the stress and deformation characteristics of the surrounding rock, the motion and deformation characteristics of the tunnel and the dynamic instability process of the tunnel were analyzed. The results show that explosive stress waves exhibit exponential attenuation above the arch crown of the tunnel, with the rate of attenuation depending on the amount of explosive used. The deformation process of the surrounding rock of the crown in the tunnel arch under the action of the explosion stress wave was compression followed by tension, which fully proves the existence of the reflected tensile wave. Movement and deformation parameters within the tunnel escalate as the explosive charge increases, especially at the crown of the arch. According to the monitoring results of the motion camera, the dynamic instability process of the tunnel was divided into several stages, such as initial calm, tunnel vibration, particle ejection, atomization, local block ejection, and return to calm. The results of the study have important reference value for the safe excavation and effective support of deep underground engineering.