scholarly journals Predicting the Healthy Operation of Heavy Oil Well Casings in Permafrost Regions

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Tiecheng Sun ◽  
Cancan Liu ◽  
Zurun Yue ◽  
Tianfei Hu ◽  
Yiming Liao
Keyword(s):  
Stress State ◽  
Heavy Oil ◽  
Soil Layer ◽  
Lateral Wall ◽  
Vertical Stress ◽  
Initial Increase ◽  
Elastic State ◽  
Maximum Settlement ◽  
Negative Friction ◽  
Distribution Of Stress

This study explores the distribution of stress and deformation on casings in heavy oil recovery wells and the distribution of stress in the thaw bulb in permafrost areas. Considering the expansion of the thaw bulb, the simulation analysis method is used to explore the internal mechanisms of vertical settlement displacement development and stress redistribution within thawed soil and casing. Calculation results show the following: (a) The maximum settlement of the thawed soil and the casing was positively correlated with the expansion of the thaw bulb. Although the settlement of the thawed soil was greater than that of the casing, the initial increase in maximum settlement difference between the thawed soil and the casing eventually tended to be constant due to stabilization of the thaw bulb’s expansion. (b) The size of the thaw bulb directly affects the redistribution of internal stress in thawed soil, leading to different distribution rules for the vertical displacement of thawed soil and casing with depth. (c) Beyond a certain formation depth, the vertical stress of thawed soil gradually transits from a tensile stress state to a compressive stress state. The depth of a soil layer whose horizontal stress value is initially greater than its vertical stress value will gradually deepen with an increase in thaw bulb radius. (d) There is no significant negative friction on the lateral wall of casing in yield state, but significant negative friction exists on the lateral wall of casing in elastic state. The vertical stress of casing in elastic state increased gradually with the increase of casing depth, due to the existence of continuous negative friction and dead weight.

scholarly journals Simulated Soil Organic Carbon Density Changes from 1980 to 2016 in Shandong Province Dry Farmlands Using the CENTURY Model

2020 ◽  
Vol 12 (13) ◽  
pp. 5384
Author(s):  
Min Tang ◽  
Shihang Wang ◽  
Mingsong Zhao ◽  
Falyu Qin ◽  
Xiaoyu Liu
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Atmospheric Carbon Dioxide ◽  
Soil Layer ◽  
Co2 Concentration ◽  
Shandong Province ◽  
Initial Increase ◽  
Century Model ◽  
Carbon Density ◽  
Soil Organic Carbon Density

The changes in cultivated soil organic carbon (SOC) have significant effects on soil fertility and atmospheric carbon dioxide (CO2) concentration. Shandong Province is an important agricultural and grain production area in China. Dry farmland accounts for 74.15% of the province’s area, so studies on dynamic SOC changes would be helpful to understand its contribution to the Chinese national carbon (C) inventory. Using the spatial overlay analysis of the soil layer (1:10,000,000) and the land use layer (1:10,000,000), 2329 dry farmland soil polygons were obtained to drive the CENTURY model to simulate SOC dynamics in Shandong Province from the period 1980 to 2016. The results showed that the CENTURY model can be used to simulate the dry farmland SOC in Shandong Province. From the period 1980 to 2016, the soil organic carbon storage (SOCS) and soil organic carbon density (SOCD) showed an initial increase and then decreased, especially after reaching a maximum in 2009. In 2016, the SOCS was 290.58 × 106 t, an increase of 26.99 × 106 t compared with 1980. SOCD in the dry farmland increased from 23.69 t C ha−1 in 1980 to 25.94 t C ha−1 in 2016. The dry farmland of Shandong Province was a C sink from 1980 to 2016. Among the four soil orders, inceptisols SOCD dominated, and accounted for 47.81% of the dry farmland, followed by >entisols > vertisols > alfisols. Entisols SOCD growth rate was the highest (0.23 t C ha−1year−1). Compared to 1980, SOCD in 2016 showed an increasing trend in the northeast, northwest and southeast regions, while it followed a downward trend in the southwest.

Study on the Bearing Mechanism of Squeezed Branch Pile Based on BOTDR

2011 ◽  
Vol 368-373 ◽  
pp. 2065-2070
Author(s):  
Chun De Piao ◽  
Yong Zhao Qu
Keyword(s):  
Soil Layer ◽  
Load Test ◽  
Static Load Test ◽  
Pile Head ◽  
Sensing Technology ◽  
Side Resistance ◽  
Load Carrying ◽  
Optical Fiber Sensing ◽  
Negative Friction ◽  
Distributed Optical Fiber

Based on BOTDR distributed optical fiber sensing technology, this paper studies the variation law of branch pile axial force under the action of pile head loads and the action characteristic of pile side resistance during static load test. The result shows that: the branch of squeezed branch pile, as the major load-carrying object, bears most of the pile head loads and its function gradually emerges with increasing pile head loads. Under the action of pile head loads, the settlement and compression value of branch pile is elevated, which gradually brings about free face between branch and its overlaying soil layer. When the load exceed certain amount, the overlaying soil body of branch cracks under pile-soil interaction, and gradually loses its structural properties, because of which its settlement emerges and negative friction subsequently generated. Thus, during the design of branch pile, one should improve the properties of the soil layer around branch pile, enhance the strength of pile shaft, and lessen pile compressing deformation and settlement, so as to elevate the bearing capacity of branch pile.

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

The Research on Earth Pressure behind Inclined Retaining Wall Considering Arching Effects

2013 ◽  
Vol 790 ◽  
pp. 410-413
Author(s):  
Jian Ming Zhu ◽  
Qi Zhao
Keyword(s):  
Stress State ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Vertical Stress ◽  
Soil Arching ◽  
Active Pressure ◽  
Passive Pressure ◽  
The Earth ◽  
Two Factors

The earth pressure behind inclined wall considering the soil arching effects which was decided by two factors, the coefficient and average vertical stress, was necessary to research. Based on the analysis of stress state behind the retaining wall, the unified solution of active pressure and passive pressure was derived and was used to calculate both the magnitude and point of application. According to examples, as the angle of inclined retaining wall increasing which was signifying by , the arching effects would be also increasing which the soil was in the passive limit and be falling which the soil was in the active limit.

Dynamic Response of Underground Structure under Vertical Earthquake Action

2011 ◽  
Vol 105-107 ◽  
pp. 1480-1483 ◽  
Author(s):  
Chao Sun ◽  
Qing Wang
Keyword(s):  
Numerical Simulation ◽  
Dynamic Response ◽  
Underground Structure ◽  
Soil Layer ◽  
Vertical Stress ◽  
Compressive Deformation ◽  
Bottom Plate ◽  
Underground Structures ◽  
The Earth ◽  
Earthquake Action

The research of stability of underground structures under earthquake action is one of the hot topics in Geotechnical Engineering researches .Through numerical simulation the article studies the dynamic response rules of the underground structure under vertical earthquake action. The result shows that under vertical earthquake action the vertical stress on the roof and bottom plate of underground structure and the same depth in the earth both increases, and the vertical stress on the roof and bottom plate of underground structure is much higher than that on the same depth in the earth (above two times); under vertical earthquake action the underground structure experiences greater vertical stress from time to time, and produces vertical compressive deformation, and sometimes it completely separates from the above soil layer.

Implementation of Incremental Yield Condition for Continual Problems with Singularity

2019 ◽  
Vol 974 ◽  
pp. 620-626 ◽  
Author(s):  
Sergey Y. Kalashnikov ◽  
Elena Gurova ◽  
Renat Kuramshin ◽  
Vladimir Kharlanov
Keyword(s):  
Stress State ◽  
Plastic Material ◽  
Limit State ◽  
Yield Condition ◽  
Initial Moment ◽  
Elastic State ◽  
Uniform Stress ◽  
Uniform Stress State ◽  
Analytical Expressions ◽  
State Criterion

The limit elastic state of an infinitely large half-plane under the action of concentrated vertical and horizontal forces has been considered. The gradient yield condition specifying the elasto-plastic material yielding initial moment at non-uniform stress state is used as the limit state criterion. The analytical expressions allowing to interpret the result in the singular point have been derived.

Cutting Roof Roadway Regional Stress Characteristics Numerical Analysis of Thin Coal Seam Group

2014 ◽  
Vol 522-524 ◽  
pp. 1382-1385
Author(s):  
Zhen Wen Liu ◽  
Tao Qin
Keyword(s):  
Stress State ◽  
Numerical Analysis ◽  
Stress Concentration ◽  
Coal Seam ◽  
Rock Burst ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
State Characteristic ◽  
Regional Stress ◽  
Thin Coal Seam

The stress state characteristic of the cutting roof roadway region was simulated and analyzed by FLAC3D. The results showed that the low side of return airway and gas roadway had higher vertical stress while the horizontal stress concentration was obviously in floor and low side of the return airway, the stress of cutting roof roadway was obviously, thus the level of rock burst hazard increased. range of stress concentration are 5~10m when using cutting roof roadway, thus distance between two cutting roof roadway are no less than 20m, to avoid stress concentration regions by two adjacent cutting roof roadway superposition.

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