爆破扰动下邻近层状围岩隧道的稳定性与振速阈值

爆炸荷载下邻近既有层状围岩隧道的迎爆侧易发生开裂、破坏，确保既有隧道围岩在爆破扰动下的安全是隧道近接施工中的关键问题。基于弹性力学和结构力学原理，建立了既有层状围岩隧道迎爆侧最危险点的简化力学模型，得到了最危险点的应力计算表达式，分析了隧道半径与岩层厚度的比值、岩层的倾角、岩层所对应的圆心角和隧道埋深等因素对既有隧道围岩稳定性的影响规律，并依据岩体最大拉应力判据确定了既有层状隧道围岩稳定的质点临界振动速度，结合地震波传播时的衰减规律，可以得出爆破施工时的最大单响药量，从而为隧道近接爆破动力扰动施工提供理论依据。

Vibration velocity threshold of a tunnel adjacent to surrounding layered rocks under blasting load

Under a blasting load,the front side adjacent to blasting in an existing tunnel surrounded by layered rocks is apt to be destroyed,and therefore it is of critical importance to keep the tunnel safe from the destructive effects of the surrounding rocks' cracks and damages that occur in a blasting disturbance.In this work,based on elastic mechanics and structural mechanics,we established a simplified mechanical model for the most dangerous point of the tunnel's blasting side,and obtained the stress formula that can calculate the stress at this point.We also analyzed the regular influence of such different factors as the ratio of the tunnel radius to the thickness of layer,the inclination angle,the central angle and depth of the surrounding layered rocks on the stress.In addition,using the theory of the maximum tensile stress,we calculated the surrounding rocks' critical vibration velocity that ensures the stability of the tunnel and obtained,according to the attenuation patterns of seismic wave propagation,the maximum charge of detonation for the construction of a new tunnel.