隧道下穿古长城掘进爆破振动现场试验与控制技术研究OA

Based on the Hongshimen Tunnel cross the ancient Great Wall project in Pinggu District,Beijing,on-site vibration monitoring and signal analysis research were conducted on the vibration effects caused by tunnel blasting construction.A multi-point monitoring system was deployed to collect vibration data on the surface of the Great Wall.The research results show that the vertical component vibration is the most significant and is a key factor affecting the structural safety of the ancient Great Wall.Based on the Hilbert-Huang transform(HHT),the time-frequency-energy characteristics of vibration signals was analyzed.It was found that the blasting energy was mainly concentrated within the range of 0.1～0.4 s and 40～60 Hz after blasting,with low overlap with the common natural frequencies of ancient buildings and low resonance risk.The regression analysis results show that when the distance between the palm face and the ancient Great Wall is less than 10 meters,the vibration velocity approaches the limit value of GB 6722-2014 Safety Regulations for Blasting,and vibration control needs to be strengthened.On this basis,a wedge-shaped groove segmented precise delayed blasting technology was proposed.The experimental results show that optimizing the slot delay time(40～60 ms)will increase the vibration reduction rate to 18％and control the vibration velocity at the ancient Great Wall below 0.2 cm/s,meeting the requirements of cultural relic protection.This research result can provide scientific basis for blasting construction of tunnels cross the cultural heritage with important reference value for similar projects.