高饱和黏土中爆炸波作用下直埋聚乙烯管的动力响应

Dynamic responses of PE pipes directly buried in high saturated clay to blast wave

为了解决爆破作业对近距离埋地管道的安全评估问题,对高饱和粘土中爆炸波作用下聚乙烯(polyethylene, PE)管道进行了一系列管道动态响应的原型实验,得到了不同药量下管道动应变、动压力的实验数据和管体及地面的振速数据。实验结果表明:PE管动应变峰值同比例距离具有良好的幂函数衰减关系,在6～11 m/kg^(1/3)比例距离范围内,PE管的环向峰值应变衰减指数(绝对值)比轴向峰值应变衰减指数大;管道动态响应的主振频率略高于土体的主振频率,两者在同一量级,管道合成速度衰减指数大体和管道轴向应变衰减指数相当;压电陶瓷片所测得的电压信号和同测点的应变变化率信号具有较强的相关性。高饱和黏性土由于含水量较高,近距离柔性PE管因受到局部冲击会产生较大的环向应变,管道安全计算时应充分考虑这一因素;随着比例距离的增大,环向应变水平降低,轴向应变水平相对增强;压电陶瓷片因为具有良好可靠的动态性能,作为埋地管道现场监测的技术手段值得采用和推广。

In order to solve the safety assessment of a buried pipeline nearby blasting operation location,a series of dynamic responses of the polyethylene(PE)pipe in high saturated clay under the action of the explosive wave were carried out.The experimental data of the dynamic strain and dynamic pressure were gotten,and the velocity data of the pipe and the ground were measured at the same time.The experimental results show that the peak strain of the PE pipe has a good power function attenuation relationship with scaled distance.In the scaled distance range of 6.11 m/kg^1/3,the attenuation index of hoop strain(absolute value)is larger than the attenuation index of axial strain.The main vibration frequency of the dynamic response of the pipeline is slightly higher than the main vibration frequency of the soil,both in the same order.The pipeline synthesis velocity attenuation index is roughly the same as the axial strain attenuation index of the pipe.There is a strong correlation between the dynamic pressure signal measured by PZT and the strain rate signal of the same point.Due to the high water content in the high saturated soil,the PE pipe will be locally impacted and the greater circumferential strain will be produced,so this factor should be taken full account of the pipeline safety assessment.The hoop strain level is reduced,and the axial strain level relatively enhances when the scaled distance increases.Because of good and reliable dynamic performance of the PZT,the PZT is worthy of use and promotion as a mean for field detection of pipelines.