Abstract
Based on the Damaoshan Highway Tunnel Reconstruction and Expansion Project, the dynamic response of adjacent tunnels during the blasting excavation of existing tunnels is analyzed by using the LS_DYNA finite element software, and the blasting vibration response and lining stress change in the blasting process are studied. Taking the particle peak vibration speed as the criterion, the traffic safety of the adjacent operating tunnels is determined. Moreover, the stress changes of the adjacent tunnel lining caused by blasting excavation are studied through the maximum principal stress. The results show that the particle peak vibration speed on the front explosion side is significantly greater than that on the back explosion side, and the maximum particle peak vibration speed on the road surface is 13 cm/s, which is greater than the allowable safety standard. Besides, the maximum principal stress on the front explosion side is about 1.5 times of that on the back explosion side, showing a “quasi-bias” phenomenon. Therefore, it is recommended to control the operation of the tunnel during the blasting process and especially focus on monitoring the vibration responses and stress changes of the lining of the operating tunnel during the construction period.
Highlights
With the rapid economic development of China, the traffic volume of highway tunnels is gradually increasing
Vibration caused by tunnel blasting has a negative effect on the surrounding rock and adjacent structures, and the in situ expansion blasting-induced vibration will affect the traffic safety of adjacent operating tunnels. erefore, research studies on the vibration control of the tunnel in situ expansion blasting process should be conducted. e current promulgated “Blasting Safety Regulations” (GB6722-2014) of China regards the peak particle vibration velocity as the index of the allowable safety standard for blasting vibration, and the allowable safety standard is set at 10–20 cm/s for traffic tunnels
The blasting vibration velocity control thresholds of some tunnels with small net distance in China are summarized in Table 2. rough the combination of engineering practice and literature analysis, the maximum vibration speed of the surrounding rock and lining of existing tunnel is 15 cm/s due to the blasting construction of the new tunnel. erefore, when the road vibration speed is less than 10 cm/s, no noticeable vibration will be aware when the car passes the tunnel in a quick speed
Summary
With the rapid economic development of China, the traffic volume of highway tunnels is gradually increasing. The dynamic response of adjacent tunnels during the blasting excavation of existing tunnels is analyzed by using the LS_DYNA finite element software, which is based on the Fujian Quan-Xia Expressway Damoshan Tunnel Expansion Project, and the blasting vibration response and lining stress change in the blasting process are studied. According to these analyses, relevant suggestions are put forward to ensure the traffic safety of the operating tunnels, and it is expected to provide valuable references for similar tunnel reconstruction and expansion projects
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