无固定墩两端埋地跨越管道自振频率计算

Calculation of Natural Frequency of Aerial Crossing Pipeline Buried at Both Ends

考虑当量轴向力和毗邻埋地管道的影响,导出了计算无固定墩两端埋地跨越管道固有频率的特征方程。在评述已有的管道频率估算公式基础上,提出了新的估算公式。计算结果表明,主要由内压、温差引起的当量轴向力对频率有较大的影响,取消锚固墩大大降低了管道的固有频率。基于特征方程的计算值,较详细地讨论了频率估算公式的可靠性,认为当量轴向力为零或拉力时,估算公式有相当的精度;当量轴向力为压力时,估算公式的误差较大,此时应按特征方程计算频率。

With the equivalent axial force (S0) and the interaction between the suspened pipeline and buried pipeline considered, the characteristic equation for calculating natural frequencies of the aerial crossing pipeline buried at both ends is derived. After frequency' estimation formulae in previous literatures are appraised,a new one is developed. Calculation results show that S0 resulting primarily from the internal pressure and the temperature difference has a great influence on natural frequencies, and that the frequencies of aerial crossing pipelines are greatly decreased with the anchors cancelled out at both ends. Based on the calculation values from the characteristic equation, investigations on reliabilities of the estimation formulae arrive at conclusions that when So is equal to zero or tensile,estimation formulae give a fair accuracy;when S0 is compressive,they give a poor accuracy,and therefore the characteristic equation should be used for frequency calculation.