Blasting Vibration Safety Criteria for Shotcrete in Underground Engineering

Abstract

Abstract The effect of seismic waves from tunnel blasts on the surrounding rock and supporting structures is an important field in underground engineering and earthquake-resistant-structure research. Damage to the rock and shotcrete surrounding a tunnel caused by blast-vibration stress waves was investigated, based on the reflection and transmission. To accomplish this, one-dimensional wave theory at different media interfaces was used. Furthermore, the allowed critical blast-vibration velocity values for different surrounding rocks and shotcrete ages were obtained. The results indicate that the damage to the supporting structure was determined by the bond strength between the shotcrete and surrounding rock, or the tensile strength of the concrete, under a blast-vibration stress wave. The resulting damage depended on the condition of the surrounding rock. At the same time, a safe distance for shotcrete supports during tunnel blasting was determined by studying the propagation of the blasting vibration through the rock. These achievements can guide the construction of underground excavations and the design of shotcrete primary supports.