To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pip...To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pipe penetration into soil is challenging for the conventional finite element(FE)method due to the large deformation of the surrounding soils.In this study,the B-spline material point method(MPM)is employed to investigate the pipe-soil interaction during the downward movement of rigid pipes buried in medium and dense sand.To describe the density-and stress-dependent behaviors of sand,the J2-deformation type model with state-dependent dilatancy is adopted.The effectiveness of the model is demonstrated by element tests and biaxial compression tests.Afterwards,the pipe penetration process is simulated,and the numerical outcomes are compared with the physical model tests.The effects of pipe size and burial depth are investigated with an emphasis on the mobilization of the soil resistance and the failure mechanisms.The simulation results indicate that the bearing capacity formulas given in the guidelines can provide essentially reasonable estimates for the ultimate force acting on buried pipes,and the recommended value of yield displacement may be underestimated to a certain extent.展开更多
Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe ...Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction (WPSI), an analytical mechanics model developed by Rajani and Tesfamariam (2004), takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction (PSI) element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.展开更多
Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil intera...Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil interactions(PSI).Analytical methods are important approaches to studying PSI.However,a systematic and thorough literature review to analyze the existing research trends,technological achievements and future research opportunities is not available.This work investigates analytical methods that analyze the stress and deformation of pipes in terms of cross-sectional,transverse and longitudinal PSI problems.First,scientometric analysis is performed to acquire relevant research works from online databases and analyze the existing data of influential authors,productive research sources and frequent key word occurrence in the fields of interest.Second,a qualitative discussion is performed in the three categories of PSI:(1)cross-sectional,including ovalization and circumferential behaviours;(2)transverse,including seismic fault crossing,weak soil zones,ground settlement and pipe uplift;and(3)longitudinal.Third,six research opportunities are discussed,including the role of friction in cross-sectional deformation,combined effects of bending and compression,choice of soil reaction models and calibration of key parameters,effect of pipe flaws,soil spatial variability and behaviours of curved pipes.This study helps beginners familiarize themselves with PSI analytical methods and provides experienced researchers with ideas for future research directions.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42225702,42077235 and 41722209).
文摘To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pipe penetration into soil is challenging for the conventional finite element(FE)method due to the large deformation of the surrounding soils.In this study,the B-spline material point method(MPM)is employed to investigate the pipe-soil interaction during the downward movement of rigid pipes buried in medium and dense sand.To describe the density-and stress-dependent behaviors of sand,the J2-deformation type model with state-dependent dilatancy is adopted.The effectiveness of the model is demonstrated by element tests and biaxial compression tests.Afterwards,the pipe penetration process is simulated,and the numerical outcomes are compared with the physical model tests.The effects of pipe size and burial depth are investigated with an emphasis on the mobilization of the soil resistance and the failure mechanisms.The simulation results indicate that the bearing capacity formulas given in the guidelines can provide essentially reasonable estimates for the ultimate force acting on buried pipes,and the recommended value of yield displacement may be underestimated to a certain extent.
基金Project supported by the National Natural Science Foundation of China (No. 50278088)the Program for New Century Excellent Talents in University (No. NCET-04-0525), China
文摘Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction (WPSI), an analytical mechanics model developed by Rajani and Tesfamariam (2004), takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction (PSI) element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.
基金The authors gratefully acknowledge the Innovation and Technology Support Programme(ITSP)[Grant No.ITS/033/20FP]the Water Supplies Department of Hong Kong,China.Suggestions given by Dr.Andy Y.F.Leung are also appreciated.
文摘Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil interactions(PSI).Analytical methods are important approaches to studying PSI.However,a systematic and thorough literature review to analyze the existing research trends,technological achievements and future research opportunities is not available.This work investigates analytical methods that analyze the stress and deformation of pipes in terms of cross-sectional,transverse and longitudinal PSI problems.First,scientometric analysis is performed to acquire relevant research works from online databases and analyze the existing data of influential authors,productive research sources and frequent key word occurrence in the fields of interest.Second,a qualitative discussion is performed in the three categories of PSI:(1)cross-sectional,including ovalization and circumferential behaviours;(2)transverse,including seismic fault crossing,weak soil zones,ground settlement and pipe uplift;and(3)longitudinal.Third,six research opportunities are discussed,including the role of friction in cross-sectional deformation,combined effects of bending and compression,choice of soil reaction models and calibration of key parameters,effect of pipe flaws,soil spatial variability and behaviours of curved pipes.This study helps beginners familiarize themselves with PSI analytical methods and provides experienced researchers with ideas for future research directions.
文摘利用改进的渗透装置试验研究了细颗粒(0.075~1 mm)含量相同时骨架颗粒组成含量不同对散粒土的管涌发生临界条件以及颗粒侵蚀流失规律的影响,结果表明:不同颗粒级配的试样在管涌发生前,水力梯度与渗流速度呈线性关系,基本符合达西定律;骨架颗粒1~2、2~3、3~5 mm 3个粒径段对管涌发展起到了阻碍作用,其中1~2 mm粒径段颗粒对管涌孔隙的堵塞作用强于另外两个粒径段颗粒;对于不同级配的骨架颗粒,其不均匀系数越大,试样的下限临界水力梯度值就越大,细颗粒越不易起动,发生管涌的时间越晚,而不同级配的骨架颗粒对试样的上限临界水力梯度影响较小。
基金Project(52078129)supported by the National Natural Science Foundation of ChinaProjects(KYCX22_0268,SJCX21_0031)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
