冻土冻胀及其对管道的作用分析

在冻土区敷设长输管道需要考虑冻土冻胀对管道的作用,以防止管道出现过大的应力或应变而危及管道的安全运行。针对冻土冻胀作用对管道的影响提出了分析计算方法,包括冻土冻胀量计算、管道周围温度场计算模型、管道与土壤的相互作用模型以及基于应变的管道失效判据。其中,冻土冻胀量的计算主要基于冻土分凝势和蠕变,温度场模型根据考虑地面环境温度变化和管输介质的温度,管道与土壤的相互作用模型计算差异冻胀情况下管道的应力与应变。计算分析了在温度降低过程中土壤的冻结深度和冻胀位移,以及管道在冻胀作用下的变形,结果表明,冻土差异性冻胀引起管道弯曲变形,其最不安全位置发生在两种土壤的交界处附近。

The Frost Heave of Frozen Soil and Its Effect on the Pipeline

Frost heave must be considered in case that a long distance pipeline is laid in permafrost regions in order to prevent the pipeline from too high stress or strain and keep the safe operation of the pipeline. The method for analyzing the pipeline influenced by the frost heaving is proposed, including frost heave calculation, the calculation of temperature field model around the pipeline, the pipeline/soil interaction model and strain-based failure criteria. Among them, the calculation of frost heave is mainly based on permafrost segregated potential and creep, temperature field model considers environment temperature change on the ground and medium temperature inside the pipeline, the pipe and soil interaction model is used to calculate the stress or strain of the pipeline across differential frost soil. The frozen depth, frost heave and pipeline deformation are calculated in the process of temperature decrease. The results show that frost heave causes pipeline bending deformation, andthe most unsafe position is located near the intersection of two soils.