季节性冻土区轴向双腐蚀管道地震时程效应分析

Seismic time history effect analysis of axial double corroded pipeline in seasonal frozen soil area

针对冻土区埋地含双腐蚀管道的抗震性能问题,以含双腐蚀管道、保温层及季节性冻土区土壤为研究对象,提出将粘弹性边界条件施加在土体周围以保证模型的准确合理,分析了在差异性冻胀和地震波作用下,含不同腐蚀参数管道的力学特性。结果表明:随着腐蚀长度与腐蚀深度的增加,R_(1)点处轴向应变峰值发生改变,腐蚀长度的变化使R_(1)点峰值最大改变为从-0.0054增大到-0.00175,增加了0.00365,腐蚀深度的变化使R_(1)点峰值最大改变为从0.00214减小到-0.0054,减小了0.00754;与腐蚀长度相比,腐蚀深度对腐蚀区中心位置的von Mises等效应力与轴向应变的影响较大;在地震波作用过程中,双腐蚀之间依然存在相互作用,腐蚀间距的增加会减轻腐蚀之间的相互作用,R_(1)点处von Mises等效应力先于R_(2),R_(3)点超过参考应力形成破坏;不同地震波作用在腐蚀缺陷处所引起的破环形式不同;将von Mises等效应力超过参考应力作为管道安全评价标准是偏于安全的。该研究可为地震波作用下冻土区埋地含双腐蚀管道的安全评定提供一定理论参考。

For the problem of seismic performance of buried double-corrosion-containing pipeline in permafrost area,by taking double-corrosion-containing pipeline,insulation layer and seasonal permafrost area soil as the research object,it was proposed to impose the viscoelastic boundary condition around the soil body to ensure the accuracy and reasonableness of the model,and analyze the mechanical properties of the pipeline containing different corrosion parameters under the action of differential freezing expansion and seismic wave.The results show that:With the increase of corrosion length and corrosion depth,the peak axial strain at the R_(1)point changes,the change of corrosion length makes the maximum change of the peak value at the R_(1)point increase from-0.0054 to-0.00175,which is increased by 0.00365,and the change of corrosion depth makes the maximum change of the peak value at the R_(1)point decrease from 0.00214 to-0.0054,which is increased by 0.00754;Compared with the corrosion length,the corrosion depth has a greater effect on the von Mises equivalent stress and axial strain at the center of the corrosion zone;There is still interaction between the double corrosion in the process of seismic wave action,and the increase of corrosion spacing will reduce the interaction between the corrosion,and the von Mises equivalent stress at the point of R_(1)exceeds the permissible stress at the points of R_(2)and R_(3)to form a damage first.Different seismic waves acting at the corrosion defects caused by the ring-breaking form is different;Using the von Mises equivalent stress exceeding the reference stress as the pipeline safety evaluation criteria is on safety side.This study can provide some theoretical references for the safety evaluation of buried double corrosion pipelines in permafrost area under seismic wave action.