Abstract:
Nayong Weima stone arch bridge and the new simply supported beam bridge have a 41° diagonal
crossing in the horizontal direction,with a total length of 68 m. It passes 28. 5 m below the fifth span of the new
bridge,and is only 0. 8 m away from the #4 column of the new bridge. In order to ensure the successful blasting demolition of the old stone arch bridge,the in-situ buffer collapse control blasting technology is adopted to ensure the
safety of the adjacent new bridge. Considering the damage to the surrounding environment caused by the blasting
demolition of the stone arch bridge,especially the damage to 4# column and the pier foundation,the horn blasting
notches is used based on the structural characteristics of the stone arch bridge and the analysis of blasting and collapse vibrations. At the same time,the blasting notch of the East-West arch foot is moved to the second abdominal
arch,and the crushing notch close to #4 column is added. For the initiation network,the sequence of " west to east
and south to north" is adopted. Other methods include adjusting the resistance line of the blast hole close to the #4
column and taking different powder factors for different blasting notches,etc. All those measures are taken to make
the stone arch bridge tends to collapse to the south with a minimum collapse size and reduce the impact of blasting on
the surrounding environment. Furthermore,the reliability and safety of the blasting demolition of the stone arch bridge
are ensured by the safety protection measures such as stacking of slag and soft soil to cushion dikes and setting up
protective shelving. According to the collapse vibration formula,the vibration velocity of the bridge deck corresponding to the #4 column of the new bridge is calculated to be 3. 9 ~ 5. 2 cm/s,which is close to the maximum vibration
velocity of 3. 879 cm/s measured by the vibration meter. It is verified that the design idea of the blasting demolition
of the stone arch bridge and the selection of the relevant parameters are scientific and reasonable. The blasting demolition has achieved ideal results,which could provide reference for similar blasting demolition projects.
Key words:
stone arch bridge; blasting demolition; blasting vibration; collapse vibration; vibration hazards; horn blasting notch