Abstract: Collapsible loess is prone to self weight collapse after soaking. The strength of loess will be greatly reduced, and it will threaten the safe operation of buried pipelines along the way. In order to study the stability of buried pipelines in collapsible loess regions, the displacements, stresses and strains of different pipe outer diameters and wall thicknesses during collapsing were analyzed based on the finite element method. The limit length that the buried pipeline could withstand in the loess disaster under certain conditions was obtained by the eigenvalue buckling theory. The results show that: increasing the outer diameter and wall thickness of the pipeline and reducing the buried depth of the pipeline in the loess can effectively reduce the displacement of the pipeline in the collapsible loess; and increasing the outer diameter and wall thickness of the pipeline can also effectively avoid the phenomenon that the local stress of the pipeline is too high; the maximum stress and strain of the pipeline occur at the center of the collapsing zone and the fixed ends on both sides; according to the buckling eigenvalue theory, the ultimate length of the collapsible area of the pipeline is about 65 m when the soil mass has self weight collapsible, and increasing the outer diameter and wall thickness of the pipeline can enhance the buckling resistance of buried pipelines when self weight collapse after soaking.

Key words: Collapsible loess, Buried pipeline, Finite element, Buckling eigenvalue analysis

摘要： 湿陷性黄土浸水后易产生自重湿陷，黄土的强度会大大降低，并对沿途埋地管道的安全运行产生威胁。为了研究埋地管道在湿陷性黄土地区的稳定性，基于有限元方法，分析了外径和壁厚不同的管道在湿陷时产生的位移、应力和应变；采用特征值屈曲理论，研究了一定条件下埋地管道在黄土灾害中所能承受的极限长度。结果表明，增大管道外径和壁厚、减少管道在黄土中的埋深，可以有效降低管道在湿陷性黄土中的位移；加大管道外径与壁厚，也可有效避免管道出现局部应力过高的现象；管道的最大应力与应变均发生在湿陷区中心和两侧固支端位置。经特征值屈曲理论分析可知，管道在土体产生自重湿陷时的湿陷区极限长度约为65 m，提高管道外径和壁厚可增强埋地管道在黄土遇水湿陷时的抗屈曲能力。

关键词: 湿陷性黄土, 埋地管道, 有限元, 屈曲特征值