水热迁移对饱和冻土应力及变形的影响

The influence of moisture-heat transfer on saturated frozen soil stress and deformation

油管道运行过程会干扰土壤温度和水分的自然运移,为了使水热迁移对冻土状态施加的扰动更为形象化,对冻土力学变化进行数值分析。对水热迁移引起的冻土骨架、孔隙结构的小范围变化进行分析。根据模拟计算结果,水热迁移对冻土施加的作用直观表现为:在环境气温低的月份,冻土应力增大,应变减小;在环境气温高的月份,冻土应力减小,应变增大;这种趋势源于环境气温变化对管道与冻土交互换热幅度及冻土水热运移状态的改变。本质原因:随温度上升,孔隙内的胶质结构被破坏,孔隙结构被挤压变形,表现为孔隙度、孔径变小,水分运移加速,对冻土骨架产生应力、压力作用,同时降低骨架强度。

The operation process of pipeline will interfere with the natural transfer of soil temperature and moisture,in order to visualize the disturbance of moisture-heat transfer on frozen soil state,this paper carries out numerical analysis for the mechanics changes in frozen soil and analyzes the small changes of frozen soil framework and pore structure caused by moisture-and heat transfer.According to the simulation results,the direct effect of moisture and heat-transfer on frozen soil is that in months with low ambient temperatures,the greater the frozen soil stress is,the smaller the strain is,and in months with high ambient temperatures,the smaller the frozen soil stress is,the greater the strain is.These trends are due to the change of heat transfer amount between pipeline and frozen soil,and moisture-heat transfer of frozen soil caused by the change of ambient temperature.The essential reason is that as the temperature rises,the structure of gum in pore is destroyed,and pore structure is extruded and deformed,which appear that the porosity and pore size become small,moisture transfer accelerates,causing stress and pressure on frozen soil framework,and reducing the framework strength.