Shield tunneling inevitably passes through a large number of pile foundations in urban areas.Thus,an accurate assessment of tunneling-induced pile displacement and potential damage becomes a critical part of shield co...Shield tunneling inevitably passes through a large number of pile foundations in urban areas.Thus,an accurate assessment of tunneling-induced pile displacement and potential damage becomes a critical part of shield construction.This study presents a mechanism research of pile-soil-tunnel interaction through Pasternak-based two-stage analysis method.In the first stage,based on Mindlin’s solution,the soil displacement fields induced by shield thrust force,cutterhead frictions,shield shell frictions and grouting pressure are derived.The analytical solution of threedimensional soil displacement field is established by introducing Pinto’s three-dimensional volume loss formula,which solves the problems that shield construction factors are not taken into account in Loganathan’s formula and only twodimensional soil displacement field can be obtained.In the second stage,based on Pasternak’s two-parameter foundation model,the analytical solution of pile displacement induced by shield tunneling in layered soil is derived.A case was found in the project of interval tunnels from Wanjiali Square to Furong District Government of Changsha Metro Line 5,where the shield tunnels were constructed near viaduct piles.The reliability of the analytical solution proposed in this study is verified by comparing with the field measured data and the results of finite element method(FEM).In addition,the comparisons of longitudinal,horizontal and vertical displacements of soil and pile foundation analyzed by the analytical solution and FEM provide corresponding theoretical basis,which has significant engineering guidance for similar projects.展开更多
At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groun...At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage.Based on Winkler model,the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived.Meanwhile,full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement,ground surface settlement trough,vertical and horizontal displacement of the pile and pile stress under three calculation conditions,i.e.,not considering groundwater effect,considering stable groundwater effect and fluid-soil interaction.The results show that the calculated value is small when the effect of groundwater is not considered;the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction,and after the shield passing,the groundwater on both sides shows a flow trend of“U”shape on the ground surface supplying to the upper part of the tunnel;the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel,the upper pile body settles,and the lower pile body deforms upward.The horizontal displacement of pile body presents a continuous“S”shape distribution,causing stress concentration near the tunnel.The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.展开更多
目的:分析全球冠状病毒研究概况及热点,为冠状病毒研究及防控提供数据和情报支撑.方法:基于Web of Science和MEDLINE数据库,利用文献计量和知识图谱等方法,对全球范围内冠状病毒研究的发展趋势、研究群体的竞争力、研究热点及前沿等进...目的:分析全球冠状病毒研究概况及热点,为冠状病毒研究及防控提供数据和情报支撑.方法:基于Web of Science和MEDLINE数据库,利用文献计量和知识图谱等方法,对全球范围内冠状病毒研究的发展趋势、研究群体的竞争力、研究热点及前沿等进行深入分析.结果:自2003年以来,冠状病毒的研究热度不断提升,中国和美国在冠状病毒研究领域的生产力和影响力均领先于世界其他各国,传染病学、病毒学、微生物学是冠状病毒研究的重点学科领域,近20年来冠状病毒的研究主要围绕SARS-CoV、MERS-CoV和畜禽类冠状病毒三大类展开.结论:未来2~3年内将会出现以COVID-19为重点的研究高峰,跨国家、跨机构、跨学科的协同攻关将会大大提升COVID-19的研究效率和缩短攻关周期.展开更多
基金Project(52078060) supported by the National Natural Science Foundation of ChinaProject(2020JJ4606)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2018IC19) supported by the International Cooperation and Development Project of Double-First-Class Scientific Research in Changsha University of Science&Technology,ChinaProject(18ZDXK05) supported by Innovative Program of Key Disciplines with Advantages and Characteristics of Civil Engineering of Changsha University of Science&Technology,China。
文摘Shield tunneling inevitably passes through a large number of pile foundations in urban areas.Thus,an accurate assessment of tunneling-induced pile displacement and potential damage becomes a critical part of shield construction.This study presents a mechanism research of pile-soil-tunnel interaction through Pasternak-based two-stage analysis method.In the first stage,based on Mindlin’s solution,the soil displacement fields induced by shield thrust force,cutterhead frictions,shield shell frictions and grouting pressure are derived.The analytical solution of threedimensional soil displacement field is established by introducing Pinto’s three-dimensional volume loss formula,which solves the problems that shield construction factors are not taken into account in Loganathan’s formula and only twodimensional soil displacement field can be obtained.In the second stage,based on Pasternak’s two-parameter foundation model,the analytical solution of pile displacement induced by shield tunneling in layered soil is derived.A case was found in the project of interval tunnels from Wanjiali Square to Furong District Government of Changsha Metro Line 5,where the shield tunnels were constructed near viaduct piles.The reliability of the analytical solution proposed in this study is verified by comparing with the field measured data and the results of finite element method(FEM).In addition,the comparisons of longitudinal,horizontal and vertical displacements of soil and pile foundation analyzed by the analytical solution and FEM provide corresponding theoretical basis,which has significant engineering guidance for similar projects.
基金Project(52078060)supported by the National Natural Science Foundation of ChinaProject(2020JJ4606)supported by the National Science Foundation of Hunan Province,China+1 种基金Project(18A127)supported by the Key Foundation of Education Department of Hunan Province,ChinaProject(2018IC19)supported by the International Cooperation and Development Project of Double-First-Class Scientific Research in Changsha University of Science&Technology,China。
文摘At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage.Based on Winkler model,the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived.Meanwhile,full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement,ground surface settlement trough,vertical and horizontal displacement of the pile and pile stress under three calculation conditions,i.e.,not considering groundwater effect,considering stable groundwater effect and fluid-soil interaction.The results show that the calculated value is small when the effect of groundwater is not considered;the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction,and after the shield passing,the groundwater on both sides shows a flow trend of“U”shape on the ground surface supplying to the upper part of the tunnel;the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel,the upper pile body settles,and the lower pile body deforms upward.The horizontal displacement of pile body presents a continuous“S”shape distribution,causing stress concentration near the tunnel.The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.
文摘目的:分析全球冠状病毒研究概况及热点,为冠状病毒研究及防控提供数据和情报支撑.方法:基于Web of Science和MEDLINE数据库,利用文献计量和知识图谱等方法,对全球范围内冠状病毒研究的发展趋势、研究群体的竞争力、研究热点及前沿等进行深入分析.结果:自2003年以来,冠状病毒的研究热度不断提升,中国和美国在冠状病毒研究领域的生产力和影响力均领先于世界其他各国,传染病学、病毒学、微生物学是冠状病毒研究的重点学科领域,近20年来冠状病毒的研究主要围绕SARS-CoV、MERS-CoV和畜禽类冠状病毒三大类展开.结论:未来2~3年内将会出现以COVID-19为重点的研究高峰,跨国家、跨机构、跨学科的协同攻关将会大大提升COVID-19的研究效率和缩短攻关周期.
