多年冻土区管道投产运行后的融沉风险

Thawing settlement risk of running pipeline in permafrost regions

寒区某管道穿越多年冻土区域,途经连续冻土、不连续冻土、岛状冻土和冻土沼泽,地质条件复杂,同时管道投产后输油温度远高于设计运行温度,实际敷设情况也与设计有很大不同,极易出现融沉问题。利用多层介质稳定导热方法建立迭代公式求解管道投产运行至今冻土层中的地基融化圈厚度,通过对气温升高、地表融化作用和冻土地温的修正,求出无保温层和有保温层两种情况下管道地基融化圈的融化深度。在此基础上,结合多年冻土地基融化下沉变形和压缩沉降变形分析,计算了管道的融沉变形量,并与管道允许的最大差异性融沉变形量进行对比,明确其融沉风险。根据冻土区的地质特征和实际工程经验,给出了3种管道融沉防治措施。(表7,图2,参7)

A pipeline in cold areas runs through permafrost regions including continuous permafrost, discontinuous permafrost, island permafrost and permafrost marsh with complex geological conditions. Due to the oil transportation temperature being far higher than the designed operating temperature of the running pipeline and the great difference between actual laying and design conditions, the pipeline is prone to thawing settlement. Iterative formula is set up by using steady heat conduction of multilayer media to calculate foundation thawing circle thickness in the permafrost since the pipeline operation. Through correction of temperature rise, surface thawing and permafrost ground temperature, thawing depth of pipeline foundation thawing circle is calculated under the condition of insulating layer and insulating layer free. On the basis, thawing deformation is calculated in accordance with the analysis of permafrost foundation thawing settlement deformation and compression settlement deformation and then it is compared with the maximum differentiated thawing deformation allowed by the pipeline to define the thawing settlement risk. Finally, three pipeline thawing settlement prevention measures are provided based on the geological features of permafrost regions and actual engineering experience. （7 Tables, 2 Figures, 7 References）