Numerical model study on influences of snow cover on the temperature field around a buried pipeline in permafrost region
Snow cover has great impacts on the hydrothermal and hydrological states of the underlying active lay-er,talik and permafrost foundation soils,as well as their mechanical properties and frost hazards.In this paper,by taking into account of the thermal interactions between the buried pipeline and the ambient environment under the dual action of multiple ground freeze-thaw cycles and dynamically changing upper boundary conditions,a coupled numerical hydrothermal model of the buried pipeline and the surrounding pipeline foundation soil is es-tablished and applied for predicting the distribution and changes of temperature fields of foundation soils of the China-Russia Crude Oil Pipeline I from Mohe to Daqing,Heilongjiang Province,China.The results show that different upper boundary conditions in the same area have great influences on the temperature field of foundation soils,especially when the actual conditions of snow cover are considered in the upper boundary conditions.Snow cover will greatly affect the distribution of temperature field around the pipe foundation soils and the active layer thickness.At the 30th year of pipeline operation,the maximum thaw depth in the foundation soils under the boundary conditions with snow cover and without on the ground surface would be 6.32 m and 5.39 m,respectively.Snow cover has a good thermal insulation effect on the underlying pipe foundation soils in winter,leading to rising ground temperatures and accelerated melting of ground ice around the pipelines and deepening of the permafrost thaw under the pipeline.Under the condition of the pipeline right-of-way with snow cover,the minimum ground temperature at the depth of 0.05 m and 1 m under the mineral soil surface would be about 4.5℃ and 2.4℃ higher than that without snow cover,and the occurrence date of the annual minimum ground temperature would be about 10 days later than that without snow cover.Therefore,proper mitigative measures should be taken in the pipeline design,construction and operation phases to effectively reduce the joint thermal influences of the pipelined oil-flows and snow cover on the pipeline foundation soils.
permafrost regionssnow coverfoundation soilground temperaturenumerical model simulation
万方数据
维普
