多年冻土区原油管道地基土融沉等级可拓云评价

Extensible cloud evaluation on thaw-settlement grade of foundation soil of crude oil pipeline in permafrost regions

全球气候变暖加剧了多年冻土退化,冻土融化下沉严重威胁管道的安全运营,准确评价管基土融沉风险等级显得尤为重要。选取含水率、孔隙比、含冰量、超塑含水率4个重要的融沉影响因素,通过熵值法对各指标进行客观赋权,采用可拓云模型对多年冻土区管基土融沉等级进行评价。评价模型在中俄原油管道漠大线的实践应用表明:现行规范对多年冻土区管基土评价指标单一、界限含水率过大,同时k-means评价融沉等级界限相对模糊,而熵值-可拓云模型能够避免融沉指标界限模糊、影响因素间的不确定性,使评价结果更符合实际情况,可为多年冻土区管道的设计、运营管理中的融沉防护方案提供科学依据与理论参考。

Global warming has intensified the degradation of permafrost,and the thaw settlement of frozen soil can seriously threaten the safe operation of pipelines.Hence,it is very important to accurately evaluate the thaw settlement risk level of pipeline foundation soil.Herein,the four important factors influencing the thaw settlement,i.e.,moisture content,void ratio,ice content and superplastic moisture content,were selected and weighted objectively by the entropy method,and on this basis,the thaw-settlement grade of pipeline foundation soil in permafrost regions was evaluated with the extensible cloud model.Through the practical application of the evaluation model in Mohe–Daqing section of China–Russia Crude Oil Pipeline,the results show that,in current standards,there are no sufficient indicators for evaluating pipe foundation soil,the limit moisture content is too large,and the boundary of thaw-settlement grade in k-means evaluation is not very clear.Instead,the entropy-extensible cloud model could avoid the blurring of the thaw settlement indicators and the uncertainty among the influencing factors,so that the evaluation results are more consistent with the actual situation.Therefore,this study could provide a scientific basis and theoretical reference for the protection against thaw settlement during the design and operation management of pipeline in permafrost regions.