中俄原油管道地基土冻融及热学性质试验研究

中俄原油管道是我国能源战略通道之一，管道穿越大兴安岭多年冻土区，工程地质条件十分复杂，尤其是在伊勒呼里山附近，冻胀和融沉严重影响了管道的正常运营. 为了研究伊勒呼里山附近多年冻土的冻融性质与热学性质，对该区段内的冻土进行冻胀、融沉及导热系数试验，并对试验数据进行回归分析与影响因素分析. 研究结果表明:细粒土塑性指数小于10时，冻胀率不一定随初始含水量的增加而增加，在研究区域内进行管道垫层施工或挖填材料选择时应选用砂砾或碎石，并做好防排水措施；融沉系数随含水量的增加而增大，随干密度的增加而减小，其中粉土对融沉作用十分敏感，不适合作为管道地基，而细砾才是最佳的冻土地基；导热系数分别随总含水量和干密度的增大而增大，其中粗粒土的导热系数大于细粒土，而冻土的导热系数则比融土的高；当含水量小于10%时，融土的导热系数则高于冻土. 不同试验方法所得的结果也具有显著的差异，粗粒土扰动样的导热系数宜采用热流计法测量，细粒土扰动样的导热系数宜采用热线法测量，而原状样的导热系数宜采用比较法测量. 

Experimental Study on Frost Heave,Thaw Settlement and Thermal Properties of Foundation Soils along China-Russia Crude Oil Pipeline

The China-Russia crude oil pipeline is one of the strategic energy channels of China. The pipeline passes through the permafrost region of the Da Hinggan Mountains, where the engineering geological conditions are very complex, especially near the Yilehuli Mountains, and frost heave and thaw settlement seriously affect the normal operation of the pipeline. Experiments were therefore conducted on soils in this area to study their properties of frost heave, thaw settlement and thermal conductivity, and the test data were subjected to the regression analysis and influencing factors analysis. Results show that when the plasticity of fine-grained soils is less than 10, the frost heave ratio of soils does not necessarily increase with an increase in the initial water content. Thus, gravel and breakstone should be used as cushion and filling materials, and waterproof and drainage measures should be taken. Meanwhile, the coefficient of thaw settlement increases with water content and decreases with dry density. The silt is very sensitive to the thawing action, hence not suitable for pipe foundation, and fine gravel is the best frozen soil foundation. Besides, the thermal conductivity increases with the increase of total water content and dry density. The thermal conductivity of coarse-grained soil is higher than that of fine-grained soil, and the thermal conductivity of frozen soil is higher than that of thawed soil. However, when the water content is less than 10%, the thermal conductivity of the thawed soil is higher than that of the frozen soil. In addition, the results of thermal conductivity obtained by different test methods are significantly different. Generally, the thermal conductivity of disturbed coarse-grained soil sample should be measured by heat flow meter method, that of disturbed fine-grained soil sample should be measured by hot wire method, and that of undisturbed sample should be measured by comparison method.