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目前大多利用经验公式来估算内压卸载后的凹陷深度,并且没有估算外载荷卸载后凹陷深度的公式。以长输管线上常见的X52、X60、X70钢制管道为工程背景,运用ABAQUS软件进行管道结构力学的非线性分析,模拟了管道凹陷的形成及回弹过程。通过对比试验与数值模拟数据,验证了有限元仿真方法的可靠性。分别在外载卸载及内压卸载的情况下分析了各参数(加载深度、压头尺寸、管道尺寸、操作压力、管材性能)对凹陷回弹系数的影响。运用Matlab软件对计算结果进行非线性回归分析,得到回弹系数与各参数的关系表达式。结果表明:外载作用下凹陷的回弹系数变化范围较大,约在0.4~0.8之间;而内压卸载后凹陷的回弹系数变化范围相对较小,约在1.05~1.3之间。该研究工作有助于管道维护人员对凹陷的回弹量做出合理的估算。
At present, empirical formulas are mostly used to estimate the indentation depth after unloading, and there is no formula to estimate the indentation depth after unloading. Taking the X52, X60 and X70 steel pipes commonly found on the long-distance pipeline as the engineering background, the ABAQUS software was used to conduct the nonlinear analysis of the pipe structure mechanics to simulate the formation and rebound process of the pipeline. Through the comparison test and numerical simulation data, the reliability of the finite element simulation method is verified. The effects of various parameters (loading depth, head size, pipe size, operating pressure and pipe performance) on the springback coefficient of the recess were analyzed respectively under the conditions of external load unloading and internal pressure unloading. Using Matlab software nonlinear regression analysis of the calculation results, the relationship between the rebound coefficient and each parameter expression. The results show that the springback coefficient of the hollow under the external load varies greatly from 0.4 to 0.8, while the springback coefficient of the hollow after unloading is relatively small, ranging from 1.05 to 1.3. This research helps pipeline maintenance personnel make a reasonable estimate of the amount of springback in the sag.