不同沉降模式下埋地管道力学响应数值模拟

Numerical simulation of mechanical response of buried pipelines under different settlement modes

  • 摘要:
    目的 随着中国油气管道建设增多以及城市化进程加速,地层土体沉降导致的管道安全问题日益突出,严重威胁埋地油气管道的运行安全。地层土体沉降是一个随时间不断发展的过程灾害,相同的沉降结果可能经历了不同的沉降过程,但目前沉降作用下的管道安全评价忽略了不同沉降发展过程导致的埋地管道力学响应差异。
    方法 采用有限元数值模拟方法,通过调整同一沉降区域的沉降次数、沉降顺序,开展了不同沉降模式下的埋地管道沉降模拟,并进行了实验验证;根据模拟结果,定量对比分析了不同沉降模式下的埋地管道力学响应差异情况。
    结果 逆序阶梯沉降下的管道正上方土体地表面最大沉降量始终大于一次性整体沉降模式,且中央位置的管道底部土体分离情况也很严重,但其管道力学响应却总是小于一次性整体沉降模式。当沉降次数相同时,不同沉降顺序导致的管道力学响应差异可能超过50%,沉降过程对于沉降作用下的埋地管道的力学响应影响不容忽视;在相同沉降量下,一次性整体沉降导致的埋地管道最大沉降位移、最大纵向拉应变均超过分次多步沉降模式,其导致的埋地钢管力学响应更剧烈,管道更易因沉降而发生破坏。
    结论 对于沉降作用下的埋地管道,局部的大幅度地层土体沉降可能对管道整体力学响应的影响不大,需统一考虑整个沉降区域地层土体沉降的发展过程。对于指定沉降范围、沉降量的地层土体沉降灾害防控,为使地层土体沉降作用下的埋地管道力学响应最低,建议先对沉降区中部进行一次相对大范围的地层土体沉降分析,然后向沉降区边界分多次进行小范围地层土体沉降,研究成果对于准确评估地层土体沉降下埋地管道的安全平稳运行具有重要意义。

     

    Abstract:
    Objective The rapid expansion of oil and gas pipeline construction in China, coupled with accelerating urbanization, has heightened safety concerns from stratum soil settlement, posing significant risks to buried pipeline operations. Stratum soil settlement is a time-dependent process; although similar settlement outcomes may arise from varying development patterns, current safety evaluations overlook how these differing settlement processes affect the mechanical response of buried pipelines.
    Methods Finite element numerical simulation was employed. By varying settlement counts and sequences across different areas, simulations of buried pipeline settlement under various modes were conducted and validated experimentally. The simulation results enabled a quantitative comparison and analysis of the mechanical responses of buried pipelines under different settlement modes.
    Results Under reverse-order step-by-step settlement, the maximum surface settlement above the pipeline exceeded that of the one-time overall settlement mode. Although soil separation beneath the pipeline center was severe, the pipeline’s mechanical response remained lower than in the one-time overall settlement. When settlement counts were equal, differences in pipeline mechanical response due to settlement sequence exceeded 50%, highlighting the significant impact of settlement processes. For the same settlement amount, the one-time overall mode caused more than twice the maximum displacement and longitudinal tensile strain compared to multi-step settlement. Consequently, one-time overall settlement induced a more intense mechanical response, increasing the risk of damage to buried steel pipelines.
    Conclusion Large-scale local stratum soil settlement has limited impact on the overall mechanical response of buried pipelines. A comprehensive analysis of the settlement development across the entire area is necessary. To minimize pipeline mechanical response for a given settlement range and amount, it is recommended to first analyze large-scale settlement in the center of the area, followed by multiple smaller settlements toward the boundaries. These findings are crucial for accurately assessing the safety of buried pipelines under stratum soil settlement.

     

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