爆破振动对既有高铁隧道衬砌安全的影响分析

Impact Analysis of Blasting Vibration on the Safety of Existing High Speed Tunnel Lining

在救援通道爆破掘进施工中,为了确保邻近金山顶隧道的安全,运用现场测试技术与数值法探讨了爆破振动对邻近高铁隧道衬砌结构的振动影响。其中数值分析表明既有隧道迎爆侧受水平应力波为主,径向振速明显大于垂向振速;迎爆侧从拱顶至墙脚,径向振速先增后减,墙腰处最大,拱脚处次之,墙脚处径向振速大于拱顶处;垂向振速呈现先减小后增大趋势,拱顶处最大;既有隧道衬砌墙腰处受拉应力最大,易出现拉伸破坏。最后基于动力弹性理论,依据现场测试数据振速和混凝土动应变的关系,通过线性拟合确定了爆破施工过程中隧道衬砌安全条件下爆破振动速度不大于6 cm/s。

In order to ensure the safety of the adjacent mountain tunnel,the vibration effect of blasting vibration on adjacent high-speed railway tunnel lining structure is discussed in order to ensure the safety of the adjacent tunnel.The numerical analysis shows that detonating side of the existing tunnel suffers mainly the horizontal stress wave,radial vibration velocity is obviously greater than vertical vibration velocity. On the detonating side from the vault to the foot of the wall,radial vibration velocity increased firstly and then decreased. The maximum occurred on the wall waist,then the arch of the foot. The radial vibration velocity at the arch of the foot is greater than that at the crown.The vertical vibration velocity decreased firstly and then increased,the maximum occurred on the vault,and the maximum tensile stress occurred on the wall waist of the existing tunnel lining,prone to tensile failure. Finally based on the dynamic theory of elasticity,and on the relationship of field test vibration velocity of concrete and the dynamic strain,through linear fitting,the result show that the blasting vibration velocity should be not greater than the 6 cm/s during the blasting construction of tunnel lining under the safety conditions.