富水地层盾构掘进下近接桩-土力学响应分析
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摘要
基于富水地层透水性强、土层强度低等特性,运用盾构技术进行隧道施工造成的土层变形、临近桩体扰动等负面现象尤为突显。为探明渗流影响下由盾构掘进引起的孔压变化、桩-土响应规律,以某盾构隧道工程为依托,采用有限元数值分析方法,阐明盾构隧道在流-固耦合作用下的孔压分布、桩-土内力及位移发展形式。研究结果表明:(1)与未考虑地下水作用相比,渗流场影响下的桩体与地表土层沉降明显加剧,其沉降最大增幅分别达32.18%、31.95%;(2)盾构隧道下穿建筑桩基施工,对桩体内力值影响较大,桩体下部轴力沿埋深增长并产生负摩阻力,较大程度地抑制桩体性能发挥;(3)隧道防水失效下,周边围岩内部孔隙水压力于1倍隧道直径范围内呈现剧烈衰减,并沿水平向出现明显孔压降压带。
Due to such characteristics as strong water permeability and low soil strength of the water-rich stratum,the negative phenomena such as soil deformation and adjacent pile disturbance caused by tunnel construction with shield technology are particularly prominent.In order to ascertain the change of pore water pressure and the pile-soil response caused by shield excavation under the influence of seepage,the finite element numerical analysis method is used according to some shield tunnel project in Nanchang to illustrate the pore water pressure distribution,pile-soil internal forces and displacement development forms of shield tunnels under the fluid-solid coupling effect.The results show that:1) Compared with the one with no consideration of groundwater effect,the sedimentation of pile foundation and surface soil layer is significantly intensified under the influence of seepage field,and the maximum increase of sedimentation can be 32.18% and 31.95% respectively;2) The shield tunnel constructed underneath pile foundation in the building has a great impact on the internal force of the pile.The axial force of the lower part of the pile gradually increases along the buried depth and generates negative frictional resistance,which greatly inhibits the performance of the pile body;3) In case of inefficient tunnel waterproofing,the internal pore water pressure of the surrounding rock shows a sharp attenuation in the range of one-time tunnel diameter,and an obvious pore water pressure drop zone appears along the horizontal direction.
Due to such characteristics as strong water permeability and low soil strength of the water-rich stratum,the negative phenomena such as soil deformation and adjacent pile disturbance caused by tunnel construction with shield technology are particularly prominent.In order to ascertain the change of pore water pressure and the pile-soil response caused by shield excavation under the influence of seepage,the finite element numerical analysis method is used according to some shield tunnel project in Nanchang to illustrate the pore water pressure distribution,pile-soil internal forces and displacement development forms of shield tunnels under the fluid-solid coupling effect.The results show that:1) Compared with the one with no consideration of groundwater effect,the sedimentation of pile foundation and surface soil layer is significantly intensified under the influence of seepage field,and the maximum increase of sedimentation can be 32.18% and 31.95% respectively;2) The shield tunnel constructed underneath pile foundation in the building has a great impact on the internal force of the pile.The axial force of the lower part of the pile gradually increases along the buried depth and generates negative frictional resistance,which greatly inhibits the performance of the pile body;3) In case of inefficient tunnel waterproofing,the internal pore water pressure of the surrounding rock shows a sharp attenuation in the range of one-time tunnel diameter,and an obvious pore water pressure drop zone appears along the horizontal direction.
引文
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[15]王珊.地铁+社区模式促进南昌经济发展研究[D].南昌:南昌大学,2014.
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[20]张琼方,夏唐代,丁智.盾构近距离下穿对已建地铁隧道的位移影响及施工控制[J].岩土力学,2016,37(12):3561-3568.
[21]阮雷,孙雪兵,申兴柱,等.新建盾构隧道施工对既有铁路路基的影响研究[J].铁道标准设计,2018,62(6):99-104.
[2]He C,Wang B.Research progress and development trends of highway tunnels in China[J].Journal of Modern Transportation,2013,21(4):209-223.
[3]王吉云.近十年来中国超大直径盾构施工经验[J].隧道建设,2017,37(3):330-335.
[4]贺文波.大直径盾构近穿及下穿对填土桩基础扰动效应分析[J].公路工程,2017,42(3):11-17.
[5]严凯,席培胜,刘洋.盾构下穿群桩引起的地表沉降和桩身受力规律研究[J].安徽建筑大学学报,2017,25(2):11-14,20.
[6]华志刚.富水软弱地层盾构掘进引起邻近砌体建筑物沉降研究[J].土工基础,2016,30(2):164-167.
[7]邱龑,杨新安,等.富水砂层盾构隧道开挖面稳定性及其失稳风险的分析[J].中国铁道科学,2015,36(6):55-62.
[8]张冬梅,冉龙洲,闫静雅.注浆作用下渗漏水对隧道和地层沉降影响[J].同济大学学报(自然科学版),2017,45(4):497-503.
[9]陈书文,吴二林,陈飞.盾构隧道侧穿建筑物对其桩基的影响分析---以武汉地铁8号线为例[J].人民长江,2013,44(3):52-54.
[10]刘厚全,赖金星,汪珂,等.盾构下穿既有群桩基础受力特性数值分析[J].公路,2017,62(8):298-304.
[11]夏明耀,曾进伦.地下工程设计施工手册[M].北京:中国建筑工业出版社,1997.
[12]吴波,刘维宁,索晓明.隧道降水施工地表沉降的渗流-应力耦合分析[J].岩石力学与工程学报,2006(S1):2979-2984.
[13]吴波,高波,索晓明.地铁隧道开挖与失水引起地表沉降的数值分析[J].中国铁道科学,2004(4):60-64.
[14]谢康和,周键.岩土工程有限元分析理论与应用[M].北京:科学出版社,2002.
[15]王珊.地铁+社区模式促进南昌经济发展研究[D].南昌:南昌大学,2014.
[16]朱逢斌,杨平.盾构隧道开挖对邻近桩基影响数值分析[J].岩土工程学报,2008,30(2):298-302.
[17]俞茂宏,昝月稳,范文,等.20世纪岩石强度理论的发展---纪念Mohr-Coulomb强度理论100周年[J].岩石力学与工程学报,2000(5):545-550.
[18]熊良宵,虞利军.三种Mohr强度准则的对比分析[J].长江科学院院报,2016,33(4):81-85.
[19]赖志乐.渗流场与应力场耦合在关角隧道中的应用[D].兰州:兰州交通大学,2009.
[20]张琼方,夏唐代,丁智.盾构近距离下穿对已建地铁隧道的位移影响及施工控制[J].岩土力学,2016,37(12):3561-3568.
[21]阮雷,孙雪兵,申兴柱,等.新建盾构隧道施工对既有铁路路基的影响研究[J].铁道标准设计,2018,62(6):99-104.