Numerical modeling of tunneling effect on buried pipelines

2011 ◽  
Vol 48 (7) ◽  
pp. 1125-1137 ◽  
Author(s):  
Yu Wang ◽  
Jiangwei Shi ◽  
Charles W.W. Ng
Keyword(s):  
Urban Areas ◽  
Ground Movement ◽  
Tunneling Effect ◽  
Burial Depth ◽  
Test Results ◽  
Soil Stiffness ◽  
Bending Strain ◽  
Versus Ratio ◽  
Parametric Studies ◽  
Soil Responses

The underground space in urban areas is frequently congested with utilities, including pipelines and conduits, that are affected by underground construction, e.g., tunneling. This paper carries out finite element (FE) analyses to investigate the effects of tunneling-induced ground movement on pipelines, with special attention to the different soil responses to uplift and downward pipe–soil relative movements. A series of numerical parametric studies with 900 FE simulation runs in total is performed to encompass various combinations of ground settlement profiles, pipe dimensions, material properties, pipe burial depth, and soil properties that are typical for utility pipelines and tunnel construction in urban areas. The results are summarized in a dimensionless plot of relative pipe–soil stiffness versus ratio of maximum pipe curvature to maximum ground curvature, which can be used to directly estimate the maximum pipe bending strain and (or) to directly assess the tunneling-induced risk to pipelines. The FE results and dimensionless plot are validated against field and centrifuge test results reported in the literature. Effect of pipeline orientation with respect to the tunnel centerline is explored. It might be unconservative if design analysis only considers the case that the pipeline is perpendicular to the tunnel centerline.

Buried pipeline responses to ground displacements induced by adjacent static pipe bursting

2013 ◽  
Vol 50 (5) ◽  
pp. 481-492 ◽  
Author(s):  
Jiangwei Shi ◽  
Yu Wang ◽  
Charles W.W. Ng
Keyword(s):  
Urban Areas ◽  
Ground Surface ◽  
Soil Stiffness ◽  
Worked Example ◽  
Bending Strain ◽  
Versus Ratio ◽  
Adjacent Structures ◽  
Pipe Bursting ◽  
Parametric Studies ◽  
Ground Displacements

To minimize disruptions of economic and social activities on the ground surface in urban areas, trenchless techniques such as pipe bursting are often considered for underground pipeline construction, rehabilitation, and renewal of existing utility services. Pipe bursting, however, inevitably induces outward displacements of surrounding soil, and subsequently leads to potential damages to adjacent structures and utilities. This paper carries out finite element (FE) analyses to investigate effects of the static pipe bursting–induced ground displacements on adjacent pipelines. In total 760 FE parametric studies are performed to encompass various combinations of ground settlement profiles, pipe dimensions, material properties, and soil properties that are typical of utility pipelines and pipe bursting in urban areas. The FE parametric results are summarized in a dimensionless plot of relative pipe–soil stiffness versus ratio of maximum pipe curvature to maximum ground curvature, which can be used to directly estimate the maximum pipe bending strain and (or) directly evaluate pipeline responses to adjacent pipe bursting. A worked example is provided to illustrate usage of the dimensionless plot. It is further found that the pipe–soil interaction is similar for pipe bursting and tunneling, and the effects of both pipe bursting and tunneling on adjacent pipelines can be assessed using a unified dimensionless plot. Effects of the intersection angle between the pipe bursting centerline and adjacent pipeline are explored. The pipe responses are shown to be underestimated or unconservative when only the perpendicular case is considered in the analysis.

scholarly journals An Investigation of Effects and Safety of Pipelines due to Twin Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Shao Yu ◽  
Riyan Lan ◽  
Junhui Luo ◽  
Zhibo Duan ◽  
Shaokun Ma
Keyword(s):  
Soil Parameters ◽  
Centrifuge Model Test ◽  
Burial Depth ◽  
Buried Pipelines ◽  
Soil Stiffness ◽  
Maximum Settlement ◽  
Dimensionless Analysis ◽  
Bending Strain ◽  
Calculation Results ◽  
Subway Tunnels

To efficiently and accurately predict the effects of twin tunneling on adjacent buried pipelines, the effects of upward and downward relative pipeline-soil interactions were considered. A series of numerical parametric studies encompassing 8640 conditions were performed to investigate the responses of a pipeline to twin tunneling. Based on the dimensionless analysis and normalized calculation results, the concept of equivalent relative pipeline-soil stiffness was proposed. Additionally, expressions for the relative pipeline-soil stiffness and relative pipeline curvature and for the relative pipeline-soil stiffness and relative pipeline settlement were established, along with the related calculation plots. Relying on a comparison of prediction results, centrifuge model test results, and field measured results, the accuracy and reliability of the obtained expressions for predicting the bending strain and settlement of adjacent buried pipelines caused by twin tunneling were validated. Based on the calculation method, the maximum bending strain and maximum settlement of pipelines can be calculated precisely when the pipeline parameters, burial depth, soil parameters, and curve parameters of ground settlement due to tunneling are provided. The proposed expressions can be used not only to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling but also to evaluate the effects of single and twin tunneling on the safety of existing buried pipelines. The relevant conclusions of this article can also provide a theoretical basis for the normal service of buried pipelines adjacent to subway tunnels.

Pipe–soil interaction on free-span shoulder subject to vortex-induced vibration

2020 ◽  
Vol 57 (11) ◽  
pp. 1704-1718
Author(s):  
Zhishen Zhang ◽  
Chun Fai Leung ◽  
Yean Khow Chow
Keyword(s):  
Design Guidelines ◽  
Preliminary Evaluation ◽  
Test Results ◽  
Vortex Induced Vibration ◽  
Soil Stiffness ◽  
Centrifuge Model ◽  
Pipe Section ◽  
Model Study ◽  
Parametric Studies ◽  
Motion Amplitude

Free span refers to a subsea pipeline section that is suspended over the seabed. Such a pipe section is vulnerable to vortex-induced vibration leading to possible fatigue pipe damage. Existing studies on pipe–soil interaction on a free-span shoulder are limited and the methods provided in the commonly used design guidelines appear to rely on either plausible assumptions or simplified conditions that warrant further investigations. In this study, a centrifuge model study has been carried out to evaluate pipe–soil interaction of an embedded pipe subject to cyclic motions. Parametric studies involving effects of pipeline motion amplitude and initial embedment on pipe–soil interaction are conducted. The test results reveal that the degradation in soil stiffness can be correlated with pipeline motion cycle and amplitude. Simplified methods are then proposed for the preliminary evaluation of equivalent soil stiffness.

scholarly journals Elements of Opportunity and Poultry Farms Performance in Delta State, Nigeria

2015 ◽  
Vol 4 (4) ◽  
pp. 102
Author(s):  
Rodney A. Isiorhovoja
Keyword(s):  
Urban Areas ◽  
Formal Education ◽  
Prior Experience ◽  
T Test ◽  
Test Results ◽  
Gross Margin ◽  
Rural And Urban Areas ◽  
Rural And Urban ◽  
Significant Difference ◽  
Poultry Farmers

The paper examines the existence, if any, of differences in gross margin between rural and urban areas in Delta State, Nigeria. Data were collected from all 275 poultry farmers registered with the Delta State Ministry of Agriculture, Livestock Department. The null hypotheses was that there is no significant difference in poultry farm gross margin between locations in terms rural and urban areas; managers with formal education in agriculture and managers who have no formal education in agriculture; and managers who have and who do not have prior experience in poultry business. Data were collected from all 275 poultry farmers registered with the State Ministry Agriculture using copies of a structured questionnaire and were analyzed using frequency counts, means and T-test. Amongst the findings were: Majority of poultry business operators have low level formal education in disciplines not related to agriculture; there was a significant difference in the mean number of years of schooling and courses studied between rural and urban areas but that there was no significant difference in number of years of prior experience. The T-test results failed to reject the three null hypotheses. The study concluded that indeed elements of opportunity may vary from place to place but the ability to exploit the benefits may moderate or accentuate performance. Entrepreneurial capacity building was recommended for poultry business operators’ state wide.

scholarly journals Deriving formulations for forecasting the ultimate strength of locally dented ring-stiffened cylinders under combined axial compression and radial pressure loads

2020 ◽  
Vol 23 (3) ◽  
pp. 640-654
Author(s):  
Do Quang Thang
Keyword(s):  
Ultimate Strength ◽  
Residual Strength ◽  
Good Accuracy ◽  
Uncertainty Modeling ◽  
Radial Pressure ◽  
Mean Value ◽  
Reduction Factor ◽  
The Novel ◽  
Test Results ◽  
Parametric Studies

Introduction: This paper focuses on the derived equations to evaluate the ultimate strength of ring-stiffened cylinders with local denting damage under combined loadings. The damage generation scenarios in this research are representing the collision accidents of offshore stiffened cylinders with supply ships. Methods: Numerical analysis of structures are performed using Abaqus software after validation against the experiments from the authors. The responses from seventeen cylinder specimens are analyzed to develop the numerical methods. Results: Good accuracy results were achieved when comparing the test results and the simulation results. Parametric studies are then performed on design examples of ring-stiffened cylinders when considering both intact and damaged conditions for assessing the reduction factor. Then, the novel simple design equations to assess the residual strength of ring-stiffened cylinders after ship collision are derived based on the regression analysis. These equations have good accuracy with mean value Xm (Uncertainty modeling factor) around 1.0 and together with COV (Coefficient of Variation) lower than 5.3%. Conclusion: The accuracy and reliability of the derived equations are validated by comparing it with the existing test data in open access. It is concluded that the proposed equations have high accuracy and reliability, and convenient application for the purpose of checking the residual strength of dented offshore cylinder under ship collisions.

Effects of Local Metal Loss on Deformability of Line Pipes Subjected to Compressive Load

2005 ◽  
Author(s):  
Yoshikazu Hashimoto ◽  
Hiroshi Yatabe ◽  
Naoto Hagiwara ◽  
Noritake Oguchi
Keyword(s):  
Analytical Method ◽  
Compressive Load ◽  
Fe Analysis ◽  
Ground Movement ◽  
Metal Loss ◽  
Line Pipe ◽  
Parametric Studies ◽  
Scale Experiment ◽  
The Relationship ◽  
Good Agreement

In this paper, the deformability of line pipe with local metal loss was examined. A full-scale experiment and a finite element (FE) analysis were carried out for line pipe with local metal loss subjected to an axial compressive load. As a result, a good agreement was obtained between the analytical and experimental results. This indicated that the present analytical method was applicable to evaluate the deformability of line pipes with local metal loss subjected to a large ground movement. Parametric studies were then conducted to clarify the relationship between the geometry of the local metal loss and the deformability using the FE analytical method.

scholarly journals Experimental Study and Estimation of Groundwater Fluctuation and Ground Settlement due to Dewatering in a Coastal Shallow Confined Aquifer

2019 ◽  
Vol 7 (3) ◽  
pp. 58 ◽  
Author(s):  
Jiong Li ◽  
Mingguang Li ◽  
Lulu Zhang ◽  
Hui Chen ◽  
Xiaohe Xia ◽  
...  
Keyword(s):  
High Speed ◽  
Prediction Method ◽  
Burial Depth ◽  
Confined Aquifer ◽  
Test Results ◽  
Well Test ◽  
Ground Settlement ◽  
Empirical Prediction ◽  
Soil Settlement ◽  
Groundwater Fluctuations

The coastal micro-confined aquifer (MCA) in Shanghai is characterized by shallow burial depth, high artesian head, and discontinuous distribution. It has a significant influence on underground space development, especially where the MCA is directly connected with deep confined aquifers. In this paper, a series of pumping well tests were conducted in the MCA located in such area to investigate the dewatering-induced groundwater fluctuations and stratum deformation. In addition, a numerical method is proposed for the estimation of hydraulic parameter, and an empirical prediction method is developed for dewatering-induced ground settlement. Test results show that groundwater drawdowns and soil settlement can be observed not only in MCA but also in the aquifers underneath it. This indicates that there is a close hydraulic connection among each aquifer. Moreover, the distributions and development of soil settlement at various depths are parallel to those of groundwater drawdowns in most areas of the test site except the vicinity of pumping wells, where collapse-induced subsidence due to high-speed flow may occur. Furthermore, the largest deformation usually occurs at the top of the pumping aquifer instead of the ground surface, because the top layer is expanded due to the stress arch formed in it. Finally, the proposed methods are validated to be feasible according to the pumping well test results and can be employed to investigate the responses of groundwater fluctuations and stratum deformations due to dewatering in MCA.

A Comb Driving Magnetometer Based on Tunnel Effect

2007 ◽  
Vol 121-123 ◽  
pp. 561-564
Author(s):  
Xue Hua Tang ◽  
Zheng You ◽  
Yong Jun Yang ◽  
Hong Tao He
Keyword(s):  
Tunneling Effect ◽  
Tunnel Effect ◽  
Test Results ◽  
Magnetic Signal ◽  
Machining Processes ◽  
Fea Analysis

In this paper, a comb-driving tunneling magnetometer based on the tunneling effect is introduced. The designation, manufacture and tests of this magnetometer are discussed, including its structure, FEA analysis, machining processes and test results. The test results indicate that the chip is coincidental with the tunneling effect and the chip is capable of sensing the magnetic signal.

Land Use, Urban Design, and Nonwork Travel: Reproducing Other Urban Areas’ Empirical Test Results in Portland, Oregon

2000 ◽  
Vol 1722 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Marlon G. Boarnet ◽  
Michael J. Greenwald
Keyword(s):  
Land Use ◽  
Urban Area ◽  
Urban Design ◽  
Urban Areas ◽  
Empirical Test ◽  
The Other ◽  
Test Results ◽  
Trip Generation ◽  
New Urbanist ◽  
New Variables

Research on nonwork automobile trip generation and land use previously conducted by researchers is replicated for the Portland, Oregon, region. Additionally, new variables examining new urbanist arguments are incorporated. The results suggest that any links between land use and nonwork trip behavior act primarily by influencing trip costs, in terms of distances traveled and speeds achieved, rather than directly influencing the number of trips made. This analysis is consistent with the other research, suggesting that this model is not sensitive to errors that might arise due to the unique characteristics of the urban area under review.

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