Behavior of precast segmental utility tunnel under ground surface Explosion: A numerical study

•PSUT is more vulnerable than CUT against ground surface explosion.•Wedge-shaped shear keys improve the blast resistance of PSUT significantly.•Adequate ED bars at the top row reduce the segment slippage by more than 50%.•Shear links significantly reduce deflection response and change the failure mode. Over the past few decades, a large number of precast segmental utility tunnels have been constructed. Intensive research efforts have been devoted to understanding their performance under service and seismic loads. However, the vulnerability of precast segmental utility tunnels against accidental blast loads is seldom discussed. The present study performs a comprehensive numerical investigation on precast segmental utility tunnels against ground surface explosion. The numerical model is verified against testing data based on buried RC structures and semi-analytical equations in TM 5–855-1. Three types of precast tunnel connections are investigated, i.e., connection without shear keys, connection with trapezoid-shaped shear keys, and connection with wedge-shaped shear keys. The effects of detonation location and prestressing conditions are evaluated. The performances of precast segmental utility tunnels under low-level, medium-level and high-level threat explosions are obtained and compared with those of the conventional monolithic utility tunnel. Discussions on the dynamic responses and energy dissipation (ED) of different precast segmental utility tunnels are made. The influences of energy dissipating (ED) bar, shear link and burial depth on the dynamic responses of the precast segmental utility tunnel are also investigated numerically.