Thaw settlement is one of the common geohazard threats for safe operation of buried pipelines crossing permafrost regions, as pipes need to bear additional bending stress induced by settlement load. In the presented study, a novel coupled data analysis method was proposed for stress state estimation of buried steel pipeline under thawing settlement load. Multisource data including pipe bending strain derived by inertial measurement unit, pipe longitudinal strain derived by strain gauges, and thawing displacement loads derived by soil temperature monitoring were used to estimate the pipe’s mechanical states. Based on the derived data, finite element method-based pipe soil interaction model was established to predict pipe’s actual stress distribution. A monitored pipe segment of one crude oil pipeline in northeast China operated since 2010 was adopted as a prototype for the investigation, monitoring data derived in the last ten years was employed to predict the settlement loading, and relative accurate stress results was obtained via the established pipe soil interaction model. The mean absolute error (MAE) of the predicted pipe stresses compared with the monitoring results in 2014, 2017, and 2018 are 5.77%, 12.13%, and 13.55%, respectively. Based on the analyzed stress results, it can be found that the investigated pipe was subjected to an increasing settlement load from 2010–2016, made the bending stress increased up to 149.5 MPa. While after 2016, due to the depth of frost soil in this area is no more than 3.5 m, the thawing settlement load almost remained constant after 2016. As the investigated pipe is made by X65 line pipe steel, the von-Mises stress in pipe is much smaller than the allowable one indicating pipe’s structural safety status so far. The proposed method can also be referenced in the status monitoring of buried pipeline crossing other geological hazard regions.

中文翻译：

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多年冻土融化荷载作用下输油管道应力状态的多源监测数据耦合分析方法

解冻沉降是穿越多年冻土区的地下管道安全运行的常见地质灾害威胁之一，因为管道需要承受由沉降载荷引起的额外弯曲应力。在本研究中，提出了一种新的耦合数据分析方法，用于在解冻荷载作用下估算埋地钢管的应力状态。多源数据包括惯性测量单元得出的管道弯曲应变，应变仪得出的管道纵向应变以及土壤温度监测得出的解冻位移载荷，以估算管道的机械状态。在此基础上，建立了基于有限元法的管土相互作用模型，以预测管道的实际应力分布。以2010年以来运行的东北某原油管道的监测管段为原型进行调查，采用近十年来的监测数据预测沉降量，通过建立监测结果获得了相对准确的应力结果。管土相互作用模型。与2014年，2017年和2018年的监测结果相比，预测管道应力的平均绝对误差（MAE）分别为5.77％，12.13％和13.55％。根据分析的应力结果，可以发现，从2010年至2016年，所研究的管道承受的沉降载荷不断增加，使得弯曲应力增加至149.5 MPa。而在2016年之后，由于该地区的冻土深度不超过3.5 m，融化后的沉降荷载在2016年之后几乎保持不变。由于所研究的管道是由X65管线钢制成的，因此管道中的von-Mises应力远小于指示管道迄今为止的结构安全状态的允许应力。该方法也可用于穿越其他地质灾害区域的地下管道状态监测。