Jia Baoxin, Zhou Linli, Cui Jiaojiao, Chen Hao
School of Civil Engineering, Liaoning Technical University, Fuxin, 123000, Liaoning, China.
Sci Rep. 2021 Oct 26;11(1):21077. doi: 10.1038/s41598-021-00640-9.
In tunnel blasting excavation, it is important to clarify the attenuation law of blast wave propagation and predict the blast vibration velocity effectively to ensure safe tunnel construction and protection design. The effects of the free surface area its quantity on the blast vibration velocity are considered, and free surface parameters are introduced to improve the existing blast vibration velocity prediction formula. Based on the Tianhuan railway Daqianshiling tunnel project, field blast vibration monitoring tests are performed to determine changes in the peak blasting vibration velocity based on the blast distance and free surface area. LS-DYNA is used to establish tunnel blasting excavation models under three operating conditions; subsequently, the attenuation law of blast vibration velocity and changes in the vibration response spectrum are analysed. Results show that the free surface area and number of free surfaces enable the blast vibration velocity to be predicted under various operating conditions: a smaller free surface area results in a narrower frequency band range, whereas more free surfaces result in a narrower frequency band range. The improved blast vibration velocity prediction formula is validated using field and numerical test data. It is indicated that the improved formula is applicable to various tunnelling conditions.
在隧道爆破开挖中，明确爆破波传播的衰减规律并有效预测爆破振动速度，对于确保隧道施工安全和防护设计至关重要。考虑了自由面面积及其数量对爆破振动速度的影响，并引入自由面参数对现有的爆破振动速度预测公式进行改进。基于天环铁路大前石岭隧道工程，进行现场爆破振动监测试验，以确定基于爆破距离和自由面面积的爆破峰值振动速度变化。利用LS-DYNA建立三种工况下的隧道爆破开挖模型；随后，分析爆破振动速度的衰减规律和振动响应谱的变化。结果表明，自由面面积和自由面数量能够在不同工况下对爆破振动速度进行预测：自由面面积越小，频带范围越窄，而自由面越多，频带范围越窄。利用现场和数值试验数据对改进后的爆破振动速度预测公式进行了验证。结果表明，改进后的公式适用于各种隧道施工条件。
