The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was si...The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was simulated in a physical model test(with a similitude ratio of 1/73) in a geotechnical centrifuge. Two pipes of a supported and an unsupported section were evaluated over a testing period for simulating 20 years of actual pipeline operation with seasonal cyclically changing oil and ambient temperatures. The results show that pipe settlement of the supported pipe was 45% of settlement of the unsupported pipe. Settlement for the unsupported section was approximately 35% of the thaw bulb depth below the initial pipe elevation, only 30% of that for the supported pipe due to the influence of the supports. The final thaw bulbs extended approximately 3.6 and 1.6 times of the pipe diameter below the unsupported and supported pipe bottom elevations, respectively. The sandbag supports kept frozen during the test period because of cooling effect of the thermosyphons. The maximum bending stress induced over the 20 m span length from bearing of the full cover over the pipe would be equivalent to40% specified minimum yield strength(SMYS). Potential buckling of the pipe should be considered as the ground thaws.This study also offers important data for calibration and validation of numerical simulation models.展开更多
This paper presents the development of a liquid pressure based automatic monitoring device of the vertical displacement of oil pipeline that has good applicability to the extreme cold conditions of the permafrost regi...This paper presents the development of a liquid pressure based automatic monitoring device of the vertical displacement of oil pipeline that has good applicability to the extreme cold conditions of the permafrost region and is capable of automatic collection and transmission of monitoring data. The effectiveness of the device has been verified using total station measurement method and the results show that the device can intuitively indicate the vertical displacement of the pipe under the harmful influence of frost heaving and thaw settlement. According to the monitoring data, safety evaluation of the pipe during the monitoring period is carried out using stress-based design criteria and strain-based design criteria respectively. The analytic results with stress-based design criteria show that the pipe may be in a dangerous state while the results with strain-based design criteria show that the pipe is in a safe state. The design method with strain-based criteria is complementary to the design method with stress-based criteria. Separate use of either method is not recommended.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20030201)National Natural Science Foundation of China (41672310)+1 种基金the National Key Research and Development Program (Nos. 2017YFC0405101 and 2016YFC0802103)the Research Project of the State Key Laboratory of Frozen Soil Engineering (SKLFSE-ZY-20)。
文摘The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was simulated in a physical model test(with a similitude ratio of 1/73) in a geotechnical centrifuge. Two pipes of a supported and an unsupported section were evaluated over a testing period for simulating 20 years of actual pipeline operation with seasonal cyclically changing oil and ambient temperatures. The results show that pipe settlement of the supported pipe was 45% of settlement of the unsupported pipe. Settlement for the unsupported section was approximately 35% of the thaw bulb depth below the initial pipe elevation, only 30% of that for the supported pipe due to the influence of the supports. The final thaw bulbs extended approximately 3.6 and 1.6 times of the pipe diameter below the unsupported and supported pipe bottom elevations, respectively. The sandbag supports kept frozen during the test period because of cooling effect of the thermosyphons. The maximum bending stress induced over the 20 m span length from bearing of the full cover over the pipe would be equivalent to40% specified minimum yield strength(SMYS). Potential buckling of the pipe should be considered as the ground thaws.This study also offers important data for calibration and validation of numerical simulation models.
文摘This paper presents the development of a liquid pressure based automatic monitoring device of the vertical displacement of oil pipeline that has good applicability to the extreme cold conditions of the permafrost region and is capable of automatic collection and transmission of monitoring data. The effectiveness of the device has been verified using total station measurement method and the results show that the device can intuitively indicate the vertical displacement of the pipe under the harmful influence of frost heaving and thaw settlement. According to the monitoring data, safety evaluation of the pipe during the monitoring period is carried out using stress-based design criteria and strain-based design criteria respectively. The analytic results with stress-based design criteria show that the pipe may be in a dangerous state while the results with strain-based design criteria show that the pipe is in a safe state. The design method with strain-based criteria is complementary to the design method with stress-based criteria. Separate use of either method is not recommended.
