Experimental study on dynamic response of underground utility tunnel under surface explosion

To investigate the anti-external-blast performance of underground utility tunnel structures, field explosion tests were conducted to study the dynamic response characteristics and failure modes of cast-in-place and precast segmental utility tunnel structures subjected to the ground surface explosion. Via field explosion tests including 11 cases, the failure characteristics and dynamic responses of cast-in-place and precast segmental utility tunnels were observed under explosion with different scaled distances. And the anti-blast performance of cast-in-place and precast segmental utility tunnels was compared and analyzed. The research results indicate that both the roofs of the cast-in-place and precast segmental utility tunnel ultimately exhibit bending and shear failure, when subjected to ground surface explosion. The anti-blast performance of the cast-in-place utility tunnel is better than that of the precast segmental utility tunnel. The initiation position has a significant impact on the blast responses of the precast segmental utility tunnel, and it is unfavorable when the initiation position is above the center of the segment. Under a small-scale ground surface explosion, the damaged area of the cast-in-place utility tunnel is larger than that of the precast segmental utility tunnel. The damage of the precast segmental utility tunnel is concentrated in the section or connection joint located near the explosion center, and there is a significant residual slip between segments.