scholarly journals Coupling Interaction of Surrounding Soil-Buried Pipeline and Additional Stress in Subsidence Soil

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yahong Ding ◽  
Heng Yang ◽  
Ping Xu ◽  
Minxia Zhang ◽  
Zhenguo Hou
Keyword(s):  
Deformation Zone ◽  
Cohesive Soil ◽  
Test System ◽  
Additional Stress ◽  
Burial Depth ◽  
Buried Pipeline ◽  
Research Results ◽  
Soil Subsidence ◽  
Cohesion Less Soil ◽  
Surrounding Soil

In the process of underground resource exploitation, the induced surface subsidence easily leads to the deformation and failure of buried pipeline. And in the process of soil subsidence, the complex interaction between buried pipeline and surrounding soil occurs, which leads to deformation and additional stress in buried pipeline. In this paper, a laboratory test system is designed and developed to analyze the influence of buried depth, cohesion of soil, and angle of internal friction on stress, in order to obtain the deformation mechanism of pipe-soil and the pressure around the pipe and the distribution of additional axial stress along the pipeline. The research results show that in the process of subsidence, the synergistic deformation between the pipe and soil at both ends of the subsidence area is maintained, while there is a compressive nonsynergistic deformation zone in the soil at the top of the pipe, and the deformation zone in the cohesion-less soil and the cohesive soil presents a spire shape and an arch shape, respectively. Areas of maximum additional tensile and compressive stresses occur in the area of maximum curvature and the central position. In addition, the smaller the burial depth, the earlier the unloading phenomenon occurs; and the additional stress in buried pipe in cohesion-less soil is significantly less than that in cohesive soil, and the unloading phenomenon occurs earlier. The research results provide the basis for disaster prevention of buried petroleum transmission pipeline in subsidence process.

scholarly journals On the Dragging Trajectory of Anchors in Clay for Merchant Ships

2021 ◽  
Vol 9 (2) ◽  
pp. 118
Author(s):  
Xinqing Zhuang ◽  
Keliang Yan ◽  
Pan Gao ◽  
Yihua Liu
Keyword(s):  
Mathematical Model ◽  
Structural Integrity ◽  
Indirect Measurement ◽  
Test System ◽  
Flow Rule ◽  
Burial Depth ◽  
Proposed Model ◽  
Depth Increase ◽  
Two Parameters ◽  
The Mathematical Model

Anchor dragging is a major threat to the structural integrity of submarine pipelines. A mathematical model in which the mechanical model of chain and the bearing model of anchor were coupled together. Based on the associated flow rule, an incremental procedure was proposed to solve the spatial state of anchor until it reaches the ultimate embedding depth. With an indirect measurement method for the anchor trajectory, a model test system was established. The mathematical model was validated against some model tests, and the effects of two parameters were studied. It was found that both the ultimate embedding depth of a dragging anchor and the distance it takes to reach the ultimate depth increase with the shank-fluke pivot angle, but decrease as the undrained shear strength of clay increases. The proposed model is supposed to be useful for the embedding depth calculation and guiding the design of the pipeline burial depth.

Prestressing Buried Pipelines by Heating With Air

1993 ◽  
Vol 115 (4) ◽  
pp. 223-228
Author(s):  
G. King
Keyword(s):  
Elevated Temperatures ◽  
Lateral Stability ◽  
Buried Pipeline ◽  
Heating Equipment ◽  
Buried Pipelines ◽  
Thermally Induced ◽  
Hot Air ◽  
Compressive Stresses ◽  
Liquid Sulphur ◽  
Surrounding Soil

Buried pipelines operating at elevated temperatures experience high longitudinal compressive stresses because the surrounding soil prevents thermal expansion. At high operating temperatures, buried pipelines can push through the soil at bends and buckle catastrophically. In soft soils they can lose lateral stability, and they can develop plastic failures. Thermally induced problems can be prevented with varying degrees of success by using thicker wall pipe, higher strength steel, longer radius bends, deeper burial, better backfill compaction, and/or prestressing during construction. Prestressing is most appropriate for pipelines operating at temperatures more than 80°C above ambient. One technique for prestressing a buried pipeline, that has been found to be both easy and economical for a liquid sulphur pipeline in Alberta, is to heat it with hot air and bury it while it is still hot. Pipe diameter and prestressing temperature both have a significant impact on the kind of heating equipment that is required.

scholarly journals Additional Stress on a Buried Pipeline under the Influence of Coal Mining Subsidence

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Ping Xu ◽  
Minxia Zhang ◽  
Zhibin Lin ◽  
Zhengzheng Cao ◽  
Xu Chang
Keyword(s):  
Coal Mining ◽  
Surface Deformation ◽  
Analytical Calculation ◽  
Mining Subsidence ◽  
Ground Subsidence ◽  
Additional Stress ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Probability Integral Method ◽  
Coal Mining Subsidence

Buried pipelines influenced by coal mining subsidence will deform and generate additional stress during surface deformation. On the basis of the coordinating deformation relationship between buried pipeline and its surrounding soils, a stress analysis method of a buried pipeline induced by mining was proposed. The buried pipeline additional stresses were analyzed; meanwhile, a corresponding analysis process of the pipeline stresses was also presented during mining subsidence. Furthermore, based on the ground subsidence along the pipeline predicted in advance by the probability integral method, the additional stresses and Von Mises equivalent stresses and their distributions along the buried pipeline induced by the exploitation of a coal mining working face named 14101 were obtained. Meanwhile, a comparative analysis of additional stresses between simulation and analytical calculation was performed for the deep analysis and reliability of the results presented by the proposed methodology in this paper. The proposed method provides references for analysis of the additional stress and safety of buried pipelines under the influence of mining subsidence.

Pipeline Upheaval Buckling in Clayey Backfill and Shore Approach

2014 ◽  
Author(s):  
Alahyar Koochekali ◽  
Behrouz Gatmiri ◽  
Amirabbas Koochekali
Keyword(s):  
Water Level ◽  
Failure Mechanism ◽  
Water Levels ◽  
Burial Depth ◽  
Buried Pipeline ◽  
Soil Response ◽  
Upheaval Buckling ◽  
Soil Failure ◽  
Mean Water Level ◽  
Uplift Resistance

True estimation of soil response during pipeline upheaval buckling is a key parameter in the safe design of subsea buried pipeline. In this paper the effects of sea mean water level over the buried pipeline and the effects of pipe burial depth on the soil response during vertical buckling are investigated. For that purpose a numerical modeling of pipeline upheaval buckling in clayey backfill has been conducted. Different sea mean water levels are considered to simulate the pipeline shore approach. In addition, various pipeline burial depths are considered to predict the soil uplift resistance and the soil failure mechanism. In order to model the large penetration of pipeline into the soft clay, Arbitrary Eulerian Lagrangian (ALE) method is employed. The results reveal that in the shallow water the sea mean water level may have considerable effects on the soil failure mechanism and soil uplift resistance. In addition, as the sea mean water level and pipe burial depth increases, a new transitional failure mechanism can be observed. The mechanism is a combination of vertical sliding block mechanism and the flow-around mechanism.

Characterization of Blast Effects on Surrounding Soil: Internal Detonations in Underground Pipes

2011 ◽  
Vol 82 ◽  
pp. 302-307 ◽  
Author(s):  
Pamela Bonalumi ◽  
Matteo Colombo ◽  
Cesare Comina ◽  
Marco di Prisco ◽  
Sebastiano Foti ◽  
...  
Keyword(s):  
Ground Surface ◽  
Mechanical Parameters ◽  
Buried Pipeline ◽  
Acceleration Time ◽  
Blast Effects ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Insight Into ◽  
Surrounding Soil

Preliminary results from a series of blast tests within a buried pipeline are reported. The paper is mainly focused on the characterization of the site, providing an insight into the effects of different basting events in terms of soil mechanical parameters. The blasts have been monitored by means of accelerometers embedded in the ground and placed on the ground surface. The recorded acceleration time histories show a strong attenuation as the wave travels away from the source.

scholarly journals An Energy Solution for Predicting Buried Pipeline Response Induced by Tunneling Based on a Uniform Ground Movement Model

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Xin Shi ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Linzhao Cui ◽  
Jie Kong
Keyword(s):  
Ground Movement ◽  
Energy Solution ◽  
Additional Stress ◽  
Buried Pipeline ◽  
Movement Model ◽  
Total Potential ◽  
Calculation Results ◽  
Pasternak Model ◽  
Stress And Deformation ◽  
Final Settlement

The construction of shield tunnels inevitably causes displacement of the surrounding soil and additional stress and deformation of the buried pipeline. An energy solution for predicting the deformation of buried pipelines caused by tunneling is proposed in this study. First, based on the uniform ground movement model, the interval of the free displacement field of soil around the pipeline induced by tunneling is calculated. Then, we use the Pasternak model to establish the total potential energy equation of the tunnel-soil-pipeline interaction. The final settlement interval of the pipeline is obtained by solving the numerical calculation program with MATLAB. The calculation results of the energy solution are compared with the results of the centrifugal test and the reported theoretical solutions of Winkler and Pasternak, and then the applicability of the solution for predicting the pipeline response under different geotechnical conditions is verified. Combined with an engineering case, the energy method calculation results, numerical simulation results, and measured results are compared to obtain the most unfavorable position of the pipeline caused by tunneling. At the end of this study, the application steps of the proposed method in actual construction are summarized. These steps are used to predict pipeline response in order to take protective measures.

Strain Relief of a Buried Pipeline Due to Slope Movement

2008 ◽  
Author(s):  
Michael Martens ◽  
Richard Kania ◽  
Raymond Kare ◽  
David Topp ◽  
Frank Sander
Keyword(s):  
Ferromagnetic Materials ◽  
Slope Movement ◽  
Strain Gauges ◽  
Buried Pipeline ◽  
Strain Relief ◽  
Strain Measurements ◽  
Over Time ◽  
Surrounding Soil

Pipelines constructed through geologically active areas, over time, can experience a significant amount of strain due to slope movement. Eventually may become necessary to strain relief the pipeline to ensure its integrity, which is the removal of the surrounding soil to allow for relaxation of the pipeline. This paper looks at the issue of pipeline strain relief due to gradual slope movement and quantifying the amount of relaxation. A non-contacting electromagnetic tool, the TSC StressProbe, that responds to material strain in ferromagnetic materials and a series of strain gauges were used to take in-situ pipeline strain measurements during the strain relieving excavation.

scholarly journals Experimental Research on the Similarity of Rime Icing on a Cylinder Rotating around Its Horizontal Axis

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lei Shi ◽  
Yan Li ◽  
Wenfeng Guo ◽  
Ce Sun
Keyword(s):  
Wind Tunnel ◽  
Translational Motion ◽  
Experimental Studies ◽  
Similarity Criterion ◽  
Test System ◽  
Test Time ◽  
Shape Similarity ◽  
Rotational Model ◽  
Research Results ◽  
Ice Shapes

Ice accumulation on the blade of a wind turbine surface seriously threatens the operational safety of the turbine; therefore, the research on this problem is very important. In this paper, a new similarity criterion of icing shape for a rotational model was proposed based on the similarity criterion for translational motion models in the aviation field, and experimental studies on the similarity of the rotational model icing were carried out. To validate the similarity criterion, icing wind tunnel tests were carried out with aluminum cylinders with diameters of 40 mm and 20 mm. Key parameters for the experiment, such as wind speed, temperature, liquid water content, medium volume diameter, and test time, were selected based on the criterion. All the icing tests were carried out in a new self-designed icing wind tunnel test system based on natural low-temperature conditions. The icing shapes observed in the tests were confirmed after many repetitions. To quantitatively analyze the similarity between different sizes of ice shapes, a dimensionless method for evaluating the similarity of ice shapes of different sizes was defined based on the typical characteristics of ice shapes. The research results show that the similarity score between two sizes of ice shapes under different test conditions is 81%~90%. The accuracy and applicability of the icing shape similarity criterion were thus validated. The research results in this paper lay a theoretical and experimental foundation for exploring the icing shape similarity of a rotating model.

scholarly journals Calculation of the Vertical Strata Load of Utility Tunnel Crossing Ground Fissure Zone

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dan Zhang ◽  
Zhiping Hu ◽  
Ganggang Lu ◽  
Rui Wang ◽  
Xiang Ren
Keyword(s):  
Soil Layer ◽  
Earth Pressure ◽  
Reference Value ◽  
Additional Stress ◽  
Fissure Zone ◽  
Engineering Structures ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Utility Tunnel ◽  
Surrounding Soil

A ground fissure is a geological disaster in which the vertical dislocation of strata causes surface rupture. Ground fissures can cause extreme harm to the surface and underground buildings. Ground fissure activity can result in different settlement on the two sides of the strata, which will generate additional stress (pressure) that differs from the stress of the general stratum on underground structures across the ground fissure zone. It is essential to assess the effective stress of strata in the design of underground engineering structures across a ground fissure zone. The Xi’an ground fissure through a utility tunnel was focus of the research, and a physical model and data for oblique crossing of the 45° ground fissure were analyzed. A model of the utility tunnel structure was established, including the surrounding soil load as an active ground fissure environment. This model was used to calculate the vertical formation pressure of the overlying soil on the utility tunnel. A method to calculate the overlying load on the utility tunnel caused by ground fissure activity was proposed and compared with the calculation based on the A. Marston principle. The results showed that the ground fissure load calculation method based on the strata-holding effect can effectively calculate the earth pressure of the surrounding soil layer of the utility tunnel in the cross-ground fissure section. The results of this work provide guidance and reference value for the design of a utility tunnel in an area with the potential for a ground fissure.

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