基坑开挖爆破作用邻近压力燃气管道动力响应特性研究

Effect of excavation blast vibration on adjacent buried gas pipeline in a foundation pit

确保复杂城市环境基坑爆破开挖工程中邻近压力燃气管道的安全性是关键性问题。依托武汉地铁8号线二期竖井基坑爆破开挖工程,利用现场监测数据建立ANSYS/LS-DYNA三维有限元数值计算模型,分析计算了不同运行压力条件下埋地燃气管道的动力响应特性。研究结果表明:实际工况下管道截面峰值合振速为0.453 cm/s,单元峰值von-Mises应力4.95 MPa,压力燃气管道处于安全运行状态;管道截面峰值合振速大于其正上方地表振速,且两者存在线性关系,由此建立管道爆破振动速度的预测模型;管道截面峰值合振速、峰值von-Mises应力均位于迎爆侧,且随管道内压的增加而增加,内压为零时为最佳运行状态,由此建立了管道峰值von-Mises应力与内压、爆破参数的数学计算模型,为实际爆破工程的安全作业提供指导。

Ensuring the safety of the pressure gas pipelines near the blasting excavation projects in complex urban environments is a key issue.Based on the blasting excavation of the foundation pit of the second phase of Wuhan Metro Line 8,the 3-D finite element numerical calculation model of ANSYS/LS-DYNA was established by using the field monitoring data.The dynamic response characteristics of the buried gas pipeline under different operating pressure conditions were analyzed and calculated.The results show that the Peak Particle Velocity(PPV)of the pipeline section is 0.453 cm/s and the Peak Effective Stress(PES)is 4.95 MPa.The pressure gas pipeline is in a safe condition.The PPV of the pipeline section is greater than the surface PPV above it,and there is a linear relationship between the two of them.The prediction model of the PPVs of the pipeline can be established.The maximum PPV and PES of the pipeline section are located on the explosion side,and increase with the increase of the internal pressure of the pipeline.When the pressure is zero,it is the best operating state.Thus the mathematical calculation model of the PES and internal pressure and blasting parameters of the pipeline can be established,which can provide a guidance for the security assessment of the actual blasting projects.