穿越煤层段隧道爆破振动对围岩稳定性影响研究

Study on influence of blasting vibration on stability of surrounding rock in tunnel section passing through coal seam

为了研究穿越煤层段隧道爆破振动对围岩稳定性的影响,以滇黔省界毕镇高速公路某隧道为工程背景,运用现场实测、数值模拟及理论分析相结合的方法,探讨不同煤层厚度、砂岩顶板不同厚度条件下隧道爆破引起的围岩振动特性。研究结果表明:随着煤层厚度减小,振速峰值呈加速增加趋势,随着砂岩顶板厚度增加,振速峰值呈加速减小趋势;在各模拟工况中,工作面位置处振速峰值最大,工作面后方的振速峰值随距离变化呈先急剧减小后衰减趋于平缓的趋势;隧道不同位置受爆破振动影响各异,其中拱顶部位受爆破振动影响最显著,振速明显高于其他部位,拱肩部位次之,拱腰部位振速受到的影响最小。将数值模拟、现场监测及岩石动力学理论3种方法得出的振速对比分析,提出该隧道爆破施工安全振速标准。

In order to investigate the influence of blasting vibration on the stability of surrounding rock in the tunnel section passing through the coal seam, taking a certain tunnel of Bi-Zhen expressway on the provincial boundary of Yunnan and Guizhou as the engineering background, the vibration characteristics of surrounding rock caused by the tunnel blasting under different thickness of coal seam and sandstone roof ,were discussed by using the combined methods of field measurement, nu- merical simulation and theoretical analysis. The results showed that the peak value of vibration velocity presented an accelerating increase trend with the decreasing thickness of coal seam, while it presented an accelerating decrease trend with the increasing thickness of sandstone roof. In all the simulation conditions, the peak value of vibration velocity was the largest at the position of working face, and the peak value of vibration velocity in the rear of working face presented the trend of sharply decrease first and then gradually attenuate to be steady with the change of distance. The influence of blasting vibration on dif- ferent positions of tunnel were different, among which, the influence at the vault position was the most significant, with the obviously higher vibration velocity than the other positions, followed by the spandrel position, and the influence at the haunch position was the least. The standard of safe vibration velocity for the blasting construction of this tunnel was put forward bycomparing and analyzing the vibration velocities obtained by the numerical simulation, field monitoring and rock dynamics theory.