Physical Modelling on Buried Pipeline Response in Elasto-Viscoplastic Soils

2016 ◽  
Author(s):  
C. K. Wong ◽  
R. G. Wan ◽  
R. Wong ◽  
B. Liu
Keyword(s):  
Physical Modelling ◽  
Ground Movement ◽  
Experimental Program ◽  
System Response ◽  
Large Strains ◽  
Subgrade Reaction ◽  
Buried Pipeline ◽  
Compacted Clay ◽  
Soil Displacement ◽  
Soil Pipe

Buried pipeline systems may traverse sections of unstable soil masses. Long-term ground movement may induce large strains on the pipe over time. To maintain the integrity of the pipeline, pipeline engineers and designers need to assess the frequency of critical ground movements to perform necessary remediation such as a stress relief procedure to prolong pipeline operation. The frequency of applying necessary remediation measures will vary depending on the rate of soil displacement in elasto-viscoplastic soils such as clay. Previous experimental work on simulating soil-pipe interactions was completed extensively on granular soils such as sand. Thus, an experimental program in simulating soil-pipe interaction for buried pipes in elasto-viscoplastic soils is highlighted in this paper. The experimental setup comprises a steel soil chamber (0.9 m in width and height, 2.4 m in length) with a steel pipe (150 mm diameter) being embedded in a compacted clay inside the chamber. The pipe is subjected to relative longitudinal, vertical uplift, and horizontal transverse displacements. The equipment setup has the ability to control and vary the displacement rate of the pipe. Hence, the effect of various displacement rates on the system response or the subgrade reaction can be studied. The system response or the subgrade reaction is recorded in a data acquisition system. In this paper, preliminary results of a vertical uplift test will be compared with existing guidelines from the American Lifelines Alliance (ALA). The ALA guidelines have yet to incorporate the effect of varying soil displacement rates in determining maximum loads subjected onto a pipeline.

Effect of Soil Displacement Rate and Complex Loading on Soil-Pipe Interaction: A Physical Prototype Model

2017 ◽  
Author(s):  
C. K. Wong ◽  
R. G. Wan ◽  
R. C. K. Wong
Keyword(s):  
Complex Loading ◽  
Stress Relief ◽  
Soil Conditions ◽  
Prototype Model ◽  
Large Strains ◽  
Initial State ◽  
Soil Displacement ◽  
Physical Prototype ◽  
Soil Pipe

Buried pipeline systems may traverse sections in moving soil masses. Large strains may be accumulated in buried pipes under long-term ground movements, and it may affect the performance of the pipes. It is a common practice in that a stress relief procedure is applied to the pipe by removing the soil around the pipe to allow the pipe to spring back to its initial state. Pipeline engineers and designers need to assess the frequency of stress relief to maintain the integrity of the pipeline to prolong its operation. The frequency of applying necessary remediation measures depend on; the rate of soil displacement, soil-pipe interaction, severity of loading, and soil conditions. A physical model has been designed and fabricated to investigate these critical effects on soil-pipe interaction. This model comprises a steel circular soil chamber (1.5 m in diameter and 1.2 m in height) rested on a rail system, and a steel pipe (150–300 mm in diameter) being embedded in a compacted soil inside the chamber. This system has unique features: (i) facilitating the pipe be subjected to relative displacements in complex oblique (combined longitudinal-transverse) loading, (ii) simulating the low soil displacement rates in the field (50 mm per year), and (iii) testing of different soil types. Test results obtained from this research program will be used to evaluate the existing guidelines (e.g., American Lifelines Alliance (ALA) and Pipeline Research Council International (PRCI)).

Landslide Pipe-Soil Interaction: State of the Practice

2018 ◽  
Author(s):  
Geoffrey N. Eichhorn ◽  
Stuart K. Haigh
Keyword(s):  
Continuum Model ◽  
Physical Modelling ◽  
Ground Movement ◽  
Current Understanding ◽  
Continuum Models ◽  
Laboratory Studies ◽  
Scale Models ◽  
Fully Coupled ◽  
Flat Ground ◽  
Soil Pipe

Current understanding of pipe-soil interaction during large ground movement events is insufficient due to their infrequency and the complexity of the infrastructure. Pipeline operators currently rely on a fully coupled continuum model of a landslide and pipeline interaction, or, more commonly, on a simplification of this interface using structural beam style soil-springs to transfer soil loads and displacements to the pipeline. The basis for soil-springs are laboratory studies based largely on clean sand or pure clay, and flat ground. Owing to the use of manufactured soils and flat ground, the soil-pipe interface modelling may not be valid for landslides. The loading of a pipeline in a landslide, and how the soil-spring factors should change with space and time are reviewed and may differ from commonly adopted guidelines. Physical modelling in research is emerging to study landslides and pipelines utilizing fully instrumented scale models. In the absence of fully instrumented field pipelines, physical modelling should be used to validate continuum models.

SURFACE SETTLEMENT INDUCED BY TUNNELING IN GREENFIELD CONDITION THROUGH PHYSICAL MODELLING

2015 ◽  
Vol 76 (2) ◽  
Author(s):  
Aminaton Marto ◽  
Mohamad Hafeezi Abdullah ◽  
Ahmad Mahir Makhtar ◽  
Houman Sohaei ◽  
Choy Soon Tan
Keyword(s):  
Relative Density ◽  
Physical Modelling ◽  
Diameter Ratio ◽  
Surface Settlement ◽  
Ground Movement ◽  
Outer Diameter ◽  
Tunnel Excavation ◽  
Tunneling Method ◽  
Relative Density Of Sand ◽  
Tunnel Shield

Geotechnical conditions such as tunnel dimensions, tunneling method and soil type are few factors influencing the ground movement or disturbance.  This paper presents the effect of tunnel cover to diameter ratio and relative density of sand on surface settlement induced by tunneling using physical modelling. The aluminum casing with outer diameter of 50 mm was used to model the tunnel shield. The size of the casing was 2 mm diameter larger than the tunnel lining. The tunnel excavation was done by pulling out the tunnel shield at constant speed with a mechanical pulley. The tested variables are cover to diameter ratio (1, 2 and 3) and relative density of sand (30%, 50% and 75%). The results demonstrated that the surface settlement decreased as the relative density increased. Also, as the relative density of sand increased, the overload factor at collapse increased. The surface settlement was at the highest when the cover to diameter ratio was 2.  It can be concluded that in greenfield condition, the relative density and cover to diameter ratio affect the surface settlement.

scholarly journals NUMERICAL BENCHMARK OF STRONGLY TO LOOSELY COUPLED ASSEMBLIES USING THE TRANSIENT FISSION MATRIX METHOD

2021 ◽  
Vol 247 ◽  
pp. 06038
Author(s):  
K. Routsonis ◽  
P. Blaise ◽  
J. Tommasi
Keyword(s):  
Monte Carlo ◽  
Ad Hoc ◽  
Experimental Program ◽  
System Response ◽  
Propagation Time ◽  
Monte Carlo Code ◽  
Water Tank ◽  
Loosely Coupled ◽  
Recent Developments ◽  
Tightly Coupled

Advances in computational methods have given rise to the study and simulation of different aspects of reactor behavior. As such, topics associated with high computational costs become feasible candidates for further investigation and one of them is reactor space-time kinetics (STK). Until recently, STK simulation and point kinetics approximation were limited to deterministic codes, with Monte Carlo codes being too costly to start with. However, recent developments in this area have allowed the use of certain methods in stochastic codes. One such technique is based on the Transient Fission Matrix (TFM) model, a hybrid method that uses a system response obtained through Monte Carlo and stored in fission and time matrices as input for deterministic calculations. The result enables a view of the STK in terms of neutron propagation probability and propagation time across the system. The TFM method was applied to a simple coupled core configuration to generate a numerical benchmark. The Serpent 2 Monte Carlo code was used for the stochastic part of the calculation. The configuration consists of two fuel assemblies placed in a light water tank, with a water blade of varying width between them. TFM, flux and fission results were obtained for varying water blade widths, ranging between 0 cm and 20 cm. The data is then used to analyze the behavior of the system, as well as the effects of the coupling between the two assemblies. As the assemblies move further apart, the system slowly transitions from two tightly coupled assemblies that essentially form a single core, to two almost independent cores. This study enables to produce a benchmark for future calculations and predefine an innovative way of designing high dominant ratio configurations, required for tackling Monte Carlo residual problems. An actual experimental program could be led in ad hoc zero power reactor (ZPR), such as the KUCA reactor of Kyoto University.

Will a buried composite pipeline system fail at its joints under the effects of overburden soil, pipe operating pressurization, and traffic loads?

2020 ◽  
Vol 54 (18) ◽  
pp. 2433-2448
Author(s):  
Kwong Ming Tse ◽  
William Toh ◽  
Long Bin Tan ◽  
Heow Pueh Lee ◽  
Vincent Beng Chye Tan
Keyword(s):  
Pipeline System ◽  
Buried Pipeline ◽  
Pipe Failure ◽  
Traffic Loading ◽  
Traffic Loads ◽  
Reinforced Plastic ◽  
Overburden Soil ◽  
Predominant Factor ◽  
Pipe Joints ◽  
Soil Pipe

In real world applications, buried pipelines span across great lengths. It is inevitable that certain sections of a buried pipeline experience external loads in addition to top soil overburden, such as weights of aboveground buildings and traffic loads located directly above these sections. The present study investigated the effects of overburden soil, pipe internal pressurization, and traffic loads on fiber-reinforced plastic pipelines at various pipe sections with particular emphasis on pipe joints using finite element method. This study includes realistic modeling of traffic loading on service road running across a buried pipeline system, consisting of straight, bent, and joint sections. Our results also revealed that surcharge loading might not be a predominant factor in pipe failure or leakage issues as compared to the cyclic pipe internal pressurization. Moreover, it was also confirmed in our study that the pipe joint remained as the most critical region for pipe failure or leakage issues.

Investigating ground movements caused by the construction of multiple tunnels in soft ground using laboratory model tests

2007 ◽  
Vol 44 (6) ◽  
pp. 631-643 ◽  
Author(s):  
D N Chapman ◽  
S K Ahn ◽  
D VL Hunt
Keyword(s):  
Laboratory Data ◽  
Prediction Method ◽  
Physical Modelling ◽  
Model Tests ◽  
Ground Movement ◽  
Laboratory Model ◽  
Small Scale ◽  
Soft Ground ◽  
Ground Movements ◽  
Gaussian Curve

The prediction of the ground movements above single tunnels in soft ground is well established and can be estimated using semi-empirical methods based on the Gaussian curve. However, the prediction of ground movements associated with closely spaced multiple tunnels, in particular side-by-side (sbs) tunnels, is not as well understood, and therefore simple predictive methods for this application are currently quite limited in terms of their accuracy. This paper describes results from a series of small-scale (1/50) laboratory model tests (conducted at 1g) carried out in Speswhite kaolin clay. These tests have been conducted to gain a greater understanding of the short-term ground movements associated with closely spaced multiple (sbs) tunnels. The observed ground movement results from these tests have shown many of the characteristics observed at full-scale in the published case studies. These results are compared to the commonly used Gaussian curve prediction method and demonstrate the potential inaccuracy in this approach for predicting ground movements associated with closely spaced multiple tunnels. A method that modifies the Gaussian curve approach is also applied to the laboratory data and shows improved predictions.Key words: tunnelling, ground movements, multiple side-by-side tunnels, physical modelling, settlement prediction.

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.

Pipeline Material Strain Monitoring System in Permafrost of MoHe-DaQing Pipeline

2012 ◽  
Author(s):  
Pengchao Chen ◽  
Shibin Zhang ◽  
Shimei Yang ◽  
Zhengbin Li ◽  
Yanguang Ren
Keyword(s):  
North China ◽  
Safety Management ◽  
Ground Movement ◽  
Tensile Fracture ◽  
Large Strains ◽  
Time Data ◽  
Strain Capacity ◽  
Strain Monitoring ◽  
Slope Instabilities ◽  
Permafrost Regions

Mohe-Daqing pipeline is the first pipeline to be buried, passing through the permafrost regions of North China where the temperature in winter is about minus thirty degrees Celsius. This pipeline has been transporting large quantities of crude oil per day to northern markets of China since January 1st, 2011. It’s a significant cooperation for both Russia and China. This paper reviews the design, construction, and operational challenges of the first pipeline buried in the permafrost regions of North China. The pipeline is in so complicated geography environment that many kinds of geotechnical disaster could happen easily, including frost heave, thaw settlement, slope instabilities, and collapse and so on. Monitoring pipeline material strain in specific region is important and significant. Ground movement of the pipeline induces sufficiently large strains to the pipeline, which would cause wrinkling on the compression side of the pipe, or alternatively tensile fracture on the tensile side of the pipe. Brag fiber sensors have been located and composed on the surface of the pipe, which were used to monitor material strain real-time data at any time. Finite element pipe soil interaction and ground movement models in specific sites have been developed according to the monitoring data. Whether the generated pipeline strain is exceeded the strain capacity or not could be estimated by comparing with the strain capacity of the pipeline, which can help us to make decision for pipeline safety management and prevent pipeline damage from geotechnical disaster.

Research on Pipe-Soil Displacement Transfer Coefficient for Buried Pipeline

2011 ◽  
Vol 201-203 ◽  
pp. 2891-2895
Author(s):  
Xin Zhong Zhang ◽  
Ai Hong Han ◽  
Zong Liang Wu
Keyword(s):  
Transfer Coefficient ◽  
Seismic Design ◽  
Reliable Method ◽  
Seismic Damage ◽  
Decisive Factor ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Method Of Determination ◽  
Soil Displacement ◽  
Selection Of

In anti-seismic design of buried pipeline, selection of pipe-soil displacement transfer coefficient is the decisive factor for reasonable and stable analysis on seismic damage. This paper discusses calculation and selection of pipe-soil displacement transfer coefficient and related parameters, gives more definite, reasonable, simple, and reliable method of determination incorporating with existing achievements for analysis on seismic damage to buried pipelines. The results of analysis provide for anti-seismic design of buried pipelines with basis of reference.

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