Evolution of the Temperature Field of the Subgrade in the Permafrost Regions of the Great Khingan Mountains

2018 ◽  
Vol 46 (6) ◽  
pp. 20170085
Author(s):  
Haiping Liu ◽  
Lin Ding ◽  
Yang Yang ◽  
Meng Guo ◽  
Yiqi Wang
Keyword(s):  
Temperature Field ◽  
Great Khingan Mountains ◽  
Permafrost Regions

Establishment and Application of the Pipeline Monitoring System in Permafrost Regions in China

2020 ◽  
Author(s):  
Jianping Liu ◽  
Pengchao Chen ◽  
Hong Zhang ◽  
Baodong Wang ◽  
Xiaoben Liu
Keyword(s):  
Temperature Field ◽  
Soil Temperature ◽  
Monitoring System ◽  
Field Monitoring ◽  
Measurement Unit ◽  
Displacement Monitoring ◽  
Ground Displacement ◽  
Oil Pipeline ◽  
Strain Monitoring ◽  
Permafrost Regions

Abstract Buried pipelines in permafrost regions are inevitably subjected to some typical geohazards, such as frost heave, thaw settlement and thaw slumping. The bending or/and longitudinal strains will be induced in pipe under these types ground movement, which is the potential cause of weld joint rupture. Thus, in order to prevent pipe failure, a comprehensive monitoring system was designed and used in the Mohe-Daqing oil pipeline in the permafrost region in northeast China. The Mohe-Daqing oil pipeline is built for importing oil from Russia and its north part of 440km lays in permafrost. The monitoring system includes soil temperature field monitoring system, ground displacement monitoring system and pipe strain monitoring system. The soil temperature field monitoring system, which uses fiber brag grating sensors, can monitor the distribution of surrounding soil temperature in radial direction of pipe in order to detect the change of active ring of permafrost. The ground displacement monitoring system, which is based on a total station, can discover any subsidence or heave of the pipe itself and the embankment along the pipeline. The pipe strain monitoring system, which includes pipe stress monitoring system based on fiber brag grating sensors and inertial measurement unit (IMU) mapping, can inspect the real-time change of pipe stress and the bending strain periodically respectively. Using the comprehensive monitoring system, the important parameters that affect pipeline integrity such as pipeline temperature, stress, strain and displacement of Mohe-Daqing oil pipeline can be supervised timely and effectively. And the accuracy and reliability of the monitoring system have been verified in practical application. In this paper, detail about how these systems are designed and installed on the Mohe-Daqing oil pipeline is elucidated and the monitoring data is analyzed. Through these data, the present mechanical situation of Mohe-Daqing oil pipeline is safe, but the long-term change is critical because of the soaring oil temperature that is far high than the design temperature. The monitoring system is of great significance to ensure the safe operation of Mohe-Daqing pipeline and can provide reference for the pipeline operation in permafrost areas.

scholarly journals Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Zhang Junwei ◽  
Li Jinping ◽  
Quan Xiaojuan
Keyword(s):  
Temperature Field ◽  
Asphalt Pavement ◽  
Superficial Layer ◽  
Asphalt Pavements ◽  
Permafrost Region ◽  
Concrete Pavements ◽  
Permafrost Degradation ◽  
Thermal Stabilities ◽  
Ground Temperatures ◽  
Permafrost Regions

The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results.

scholarly journals Research on Design Method for Thermal Insulation of Oil Pipeline in Permafrost Regions

2020 ◽  
Vol 165 ◽  
pp. 01016
Author(s):  
Dongyuan Wang ◽  
Zifeng Zhao ◽  
Qiuxia Tan ◽  
Jian Yang
Keyword(s):  
Temperature Field ◽  
Thermal Insulation ◽  
Design Method ◽  
Maximum Amount ◽  
Freezing Damage ◽  
Strain Criterion ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
The Status ◽  
Permafrost Regions

The most important problems encountered in the design and operation of oil pipelines in permafrost regions are frost heaving and thawing settlement. In this paper, we conducted an investigation and analysis on the status of freezing damage of the operating oil pipelines. Based on the investigation and research, we calculated the temperature field of the oil pipeline and analysed the thawing ability under the conditions of the strain criterion. Finally, we proposed a design method for pipeline insulation and the maximum amount of thawing displacement that the pipeline can withstand. It has certain guiding significance for the thermal insulation design of oil pipelines in permafrost regions.

scholarly journals Temperature Field Distribution and Thermal Stability of Roadbed in Permafrost Regions

2021 ◽  
Vol 39 (1) ◽  
pp. 241-250
Author(s):  
Youkun Cheng ◽  
Zhenwu Shi ◽  
Fajin Zu
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Temperature Field ◽  
Frozen Soil ◽  
Western China ◽  
Insulation Material ◽  
Structural Factors ◽  
Term Operation ◽  
Thermal Stability Of ◽  
Permafrost Regions

Many highways and railways in western China are built on permafrost roadbed. Frost heave and thaw settlement might cause diseases to frozen soil roadbed, such as deformation and cracking. For long-term operation, frozen soil roadbed should be kept stable and durable. Therefore, this paper analyzes the distribution law of temperature field of roadbed in permafrost regions, under the effect of thermal stability. Based on the thermodynamic properties of permafrost, the authors analyzed the influence of engineering geological factors, roadbed structural factors, and natural environmental factors on the thermal stability of frozen soil roadbed. Next, the antifreeze mechanism of frozen soil roadbed was described, together with the calculation methods for the relevant parameters. Afterwards, the temperature field of the roadbed with low thermal conductivity insulation material was analyzed by two methods, namely, steady-state thermal analysis and transient thermal analysis, and the solving process of roadbed temperature field was explained in details. The proposed analysis method and solving algorithm were proved valid through experiments. The research results provide a reference for the reasonable design of frozen soil roadbed.

scholarly journals Study of Temperature Field and Structure Optimization for Runways in Permafrost Regions

2022 ◽  
Vol 130 (2) ◽  
pp. 1093-1112
Author(s):  
Xiaolan Liu ◽  
Yixiang Chen ◽  
Yan Zhou ◽  
Kai Zhang
Keyword(s):  
Temperature Field ◽  
Structure Optimization ◽  
Permafrost Regions

Study on a Method Monitoring Oil and Gas Pipelines in Permafrost Regions

2012 ◽  
Author(s):  
Yunbin Ma ◽  
Dongjie Tan ◽  
Ning Song ◽  
Pengchao Chen ◽  
Tao Ma
Keyword(s):  
Temperature Field ◽  
Oil And Gas ◽  
Frost Heave ◽  
Fiber Grating ◽  
Test Results ◽  
Gas Pipelines ◽  
Monitoring Method ◽  
Oil And Gas Pipelines ◽  
The Impact ◽  
Permafrost Regions

Based on conditions of oil and gas pipelines in permafrost regions, this paper demonstrates a method for monitoring pipeline stress and displacement as well as permafrost temperature field. To measure pipeline displacement, Total Station measuring technique which calculates displacement by measuring the change of pipeline sign post was adopted; and to monitor pipeline stress and temperature field of permafrost, Fiber Grating Sensing technique was used. This method has been applied to Pipeline No. A for a year, according to the test results, during the year, displacements of different degrees have been occurred to the pipeline; this pipeline was not influenced by frost heave in winter but was influenced by thaw collapse in summer. Due to this monitoring method for oil and gas pipelines in permafrost regions, the condition of permafrost and the change of pipeline under the impact of permafrost were successfully monitored; therefore, this method is effective and feasible.

Characteristics and Application of Temperature-Field Emitters

1975 ◽  
Vol 33 ◽  
pp. 144-145
Author(s):  
N. Tamura ◽  
T. Goto ◽  
Y. Harada
Keyword(s):  
Temperature Field ◽  
Electron Microscope ◽  
Field Emission ◽  
Resolving Power ◽  
High Brightness ◽  
Field Emitters ◽  
Emission Electron ◽  
Sufficient Stability ◽  
Scanning Electron ◽  
Illuminating System

On account of its high brightness, the field emission electron source has the advantage that it provides the conventional electron microscope with highly coherent illuminating system and that it directly improves the, resolving power of the scanning electron microscope. The present authors have reported some results obtained with a 100 kV field emission electron microscope.It has been proven, furthermore, that the tungsten emitter as a temperature field emission source can be utilized with a sufficient stability under a modest vacuum of 10-8 ~ 10-9 Torr. The present paper is concerned with an extension of our study on the characteristics of the temperature field emitters.

Multiple-fracturing and viewing of the same frozen sample at different depths using a low temperature FESEM

1996 ◽  
Vol 54 ◽  
pp. 820-821
Author(s):  
M.V. Parthasarathy ◽  
C. Daugherty
Keyword(s):  
Temperature Field ◽  
Low Temperature ◽  
Field Emission ◽  
Multiple Fracture ◽  
Precise Control ◽  
Cold Stage ◽  
Different Depths ◽  
Transfer Device

The versatility of Low Temperature Field Emission SEM (LTFESEM) for viewing frozen-hydrated biological specimens, and the high resolutions that can be obtained with such instruments have been well documented. Studies done with LTFESEM have been usually limited to the viewing of small organisms, organs, cells, and organelles, or viewing such specimens after fracturing them.We use a Hitachi 4500 FESEM equipped with a recently developed BAL-TEC SCE 020 cryopreparation/transfer device for our LTFESEM studies. The SCE 020 is similar in design to the older SCU 020 except that instead of having a dedicated stage, the SCE 020 has a detachable cold stage that mounts on to the FESEM stage when needed. Since the SCE 020 has a precisely controlled lock manipulator for transferring the specimen table from the cryopreparation chamber to the cold stage in the FESEM, and also has a motor driven microtome for precise control of specimen fracture, we have explored the feasibility of using the LTFESEM for multiple-fracture studies of the same sample.

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