Evaluation of Blast-Induced Ground Vibration in Urban Area for the Jakarta-Bandung HSR Tunnel #11

Tunnel #11 is one of thirteen tunnels for the first Indonesian high-speed railway (HSR) project connecting two of its biggest cities, i.e., Jakarta and Bandung. It was built using the drill-and-blast method. Since the tunnel is located in a densely populated urban area, the effect of blasting on ground vibration needs to be monitored carefully. This paper evaluates the effect of Tunnel 11 blasting on the surrounding environment through field monitoring. Four Minimate Plus units were used to monitor the blast-induced ground vibration, acceleration and air blast during the tunnel construction. Crack monitoring kits were used to measure the width of existing cracks in 61 residential houses, while 4 GPS units, 2 slope inclinometers, and 1 Robotic Total Station were used to monitor ground displacement in the residential area and slopes closest to the tunnel portal. The findings demonstrate that Tunnel 11 blasting was safe and complied with national and international standards. All monitored ground vibrations in residential areas were below PPV = 2 mm/s, while air blasts were largely maintained below 94 dB for a four-second blast duration. No structural or cosmetic damage was observed in the residential houses, as there was no noticeable widening of the existing cracks or formation of new ones in any of the inspected houses. The blasting also did not induce unwarranted ground displacement in the residential area and the monitored slopes. PPV and PPA prediction equations were developed based on 683 blast data collected, resulting in a practical blasting chart for designing future tunnel blasting. The findings of this study emphasize the vital role of monitoring ground vibration, air blast, structural damage, and ground displacement in safeguarding and controlling the adverse effects of tunnel blasting in urban areas.