Thaw settlement prevention and temperature monitor of Mohe-Daqing Crude Oil Pipeline in permafrost marsh zone

Since put into operation, Mohe-Daqing Crude Oil Pipeline has been running at positive temperature all year round, with transpot temperature much higher than the design temperature, as a result, melting of the soil around the pipeline has been sped up, making the pipeline prone to thaw settlement, posing great challenges to the pipeline security. In view of the actual operation conditions of Mohe-Daqing Crude Oil Pipeline, and engineering construction experience in permafrost zones, a scheme preventing thaw settlement combining thermal probes with coarse-grained soil filling is proposed. A 100 m long demonstration section has been constructed in K305 of Mohe-Daqing Crude Oil Pipeline, and temperature monitoring system has been installed in the surrounding soil of the demonstration section. The condition of thaw settlement prevention at the demonstration section has been analyzed by using monitored temperatures in nearly a year. The results show that installment of thermal probes has reduced the temperature of pipeline foundation, increased the cold storage of the soil, making the foundation more stable, and the coarse-gained soil filled at the bottom of pipeline can ensure the pipeline from frost heaving by thermal probes' refrigeration.