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为了研究小净距下复线隧道的施工爆破对既有隧道的影响并采取合理的主动控制,采用LS-DYNA动力有限元软件建立了不同净间距时新建隧道和既有隧道的数值模型。将测点峰值振速作为判据,得到了小净距下新建隧道爆破施工时既有隧道的振速测点布置方案及相应的爆破药量优选方案:既有隧道振速测点应布置在迎爆侧边墙距地面1.2m处;随两隧道净间距L的不断减小,应分别在L为9m、8m、7m时合理降低爆破装药量,相应的爆破炸药量建议值分别为48kg、30kg、24kg。数值试验和实测数据对比分析结果表明:在两隧道净间距L从11.9m逐渐减小为6.6m的过程中,既有线实测质点峰值振速与数值分析结果的变化趋势基本一致;合理有效地控制爆破药量,是降低既有隧道爆破振动响应、保证其安全运营的关键。研究所得结论可用于指导小净距条件下新建隧道的爆破施工,实现爆破振动效应危害的主动控制。
In order to study the influence of construction blasting on existing tunnels with small clear distance and to take reasonable active control, the numerical model of new tunnels and existing tunnels with different clearances is established by LS-DYNA dynamic finite element software. Based on the measured peak vibration velocity as the criterion, the optimal scheme of vibration velocity measuring points and the corresponding blasting dose optimization scheme of the existing tunnel under the construction of a new tunnel blasting under a small clear distance are obtained. The measurement points of the existing tunnel vibration velocity should be arranged at The side wall of the blasting explosion is 1.2m away from the ground. With the continuous decrease of the net spacing L of the two tunnels, the explosive charge should be reasonably reduced when L is 9m, 8m and 7m, respectively, and the corresponding explosive explosive charge values are respectively 48kg , 30kg, 24kg. The results of numerical analysis and comparison with measured data show that the trend of the peak velocity and the numerical analysis results of existing mass line are almost the same when the net spacing L of the two tunnels is gradually reduced from 11.9m to 6.6m. The reasonable and effective control Blasting dose is the key to reduce the vibration response of existing tunnel blasting and ensure its safe operation. The conclusions obtained from the study can be used to guide the blasting construction of the new tunnel under the condition of small spacing and achieve the active control of the hazard of blasting vibration.