基于原位监测与数值模拟方法的斜坡稳定性与管道失效风险评估

Assessment of Slope Stability and Pipeline Failure Risk Based on In‑situ Monitoring and Numerical Simulation Methods

摘要:

斜坡移动对埋地油气管道的结构完整性产生威胁，为了降低管道拉伸破坏发生灾害的概率，需要对管道的安全性进行定量评估。尽管在管道斜坡灾害的调查和预防中取得有益的成果，但只是对于斜坡灾害提出发生概率的大小，并没有对灾害发生提出准确预测。本研究基于云南输油管道 YC027‐35 边坡案例，采用 ABAQUS 结合数字高程数据与现场勘察的岩土体信息，建立管道和土壤非线性接触的三维有限元模型，在降雨工况下分析管道的拉应力、应变响应，并利用有限元强度折减法分析斜坡稳定性，结合危险性判别因子对斜坡稳定性做出评价，最后基于管道应变失效准则并结合现场原位监测对管道失效风险做出评估。结果表明，在降雨荷载下，斜坡稳定性系数为 Fr =1.02，处于欠稳定状态，与综合指标数值分析法结果一致；当斜坡滑动位移 0.4 m 时，管道拉应力达到屈服应力，当斜坡滑动位移为 0.75 m 时，管道应变值达到容许拉应变 1%，此时管道失效。管道在斜坡作用下的应力先到达极限值，其次才发生应变屈服。本文所采用的原位监测结合有限元数值模拟的方法，能够对斜坡稳定性和管道失效定量分析，该研究为管道的防治提供科学依据。

Abstract:

Slope movement poses a threat to the structural integrity of buried oil and gas pipelines. In order to reduce the probability of catastrophic failure due to pipeline tensile damage, it is necessary to conduct quantitative assessments of pipeline safety. Although useful progress has been made in the investigation and prevention of pipeline slope disasters, current studies mainly estimate the probability of occurrence without accurately predicting the actual failure. This study was based on the slope along the YC027-35 oil pipeline in Yunnan Province. A three-dimensional finite element model of nonlinear contact between pipeline and soil was established using ABAQUS, combined with digital elevation data and geotechnical information obtained from field investigation. Under rainfall conditions, the tensile stress and strain responses of the pipeline were analyzed. The strength reduction method was used to analyze slope stability, which was further assessed using a hazard identification factor. The pipeline failure risk was then evaluated based on the pipeline strain failure criterion combined with in-situ monitoring. The results indicated that under rainfall loading, the slope stability coefficient was Fr = 1.02, indicating an unstable state, which was consistent with the comprehensive index numerical analysis method. When the slope movement reached 0.4 m, the pipeline tensile stress reached the yield stress. When the slope movement increased to 0.75 m, the pipeline strain reached the allowable tensile strain of 1%, indicating the onset of failure. The pipeline stress reached its limit under slope movement, followed by strain yielding. The method of in-situ monitoring combined with finite element numerical simulation adopted in this paper can quantitatively analyze the slope stability and pipeline failure. This study provides a scientific basis for the prevention and mitigation of pipeline-related slope hazards.