上软下硬地层隧道掌子面稳定性及塌方形态
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摘要
为分析上软下硬地层对新奥法施工隧道稳定性的影响,定义掌子面软弱地层相对厚度系数无量纲参数;应用有限元模拟和强度折减相结合的方法,研究不同相对厚度系数下隧道掌子面的稳定性及其塌方形态。结果表明:软硬地层分界线在掌子面中,软弱地层相对厚度系数越大,稳定性越小;随着软弱地层相对厚度系数的增大,掌子面前方塌方范围扩大,最大位移在掌子面软弱地层中心偏下位置,应力拱的范围在扩大,且传递到掌子面下部的力更大,因此更应注重掌子面下部的加固。黏聚力和内摩擦角对掌子面稳定性的共同影响存在最优路径,沿此路径加固效果最为有效;掌子面稳定性随土体重度、开挖高度和掌子面软弱地层厚度的增大而减小;覆跨比对掌子面稳定性影响存在极值,以此作为确定隧道合理埋深的参考条件之一;地表超载只在浅埋情况下才影响掌子面的稳定性。
In order to analyze the influence of the upper-soft and lower-hard strata on the stability of the tunnel constructed by the New Austrian Tunneling Method,the dimensionless parameter of the relative thickness coefficient of the weak strata at tunnel face was defined.By means of finite element simulation combined with strength reduction method,the tunnel face stability and collapse shapes under different relative thickness coefficients were studied.Results show that,if the boundary between soft and hard strata is in tunnel face,the greater the thickness coefficient of weak strata is,the smaller the stability is.With the increase of the relative thickness coefficient of weak strata,the area of collapse in front of tunnel face is enlarged and the maximum displacement is below the center of the weak strata of tunnel face.The range of stress arch is expanding,and the force transferred to the lower part of tunnel face is greater.Therefore,more attention should be paid to reinforcing the lower part of tunnel face.There is an optimal path for the joint effect of cohesion and internal friction angle on the tunnel face stability,and the reinforcement effect along this path is the most effective.Tunnel face stability decreases with the increase of soil weight,excavation height and the thickness of weak strata.There is an extreme value for the effect of thickness-span ratio on the stability of tunnel face,which can be used as one of the reference conditions for determining the reasonable buried depth of tunnel.Surface surcharge affects the stability of tunnel face only when it is shallow buried.
In order to analyze the influence of the upper-soft and lower-hard strata on the stability of the tunnel constructed by the New Austrian Tunneling Method,the dimensionless parameter of the relative thickness coefficient of the weak strata at tunnel face was defined.By means of finite element simulation combined with strength reduction method,the tunnel face stability and collapse shapes under different relative thickness coefficients were studied.Results show that,if the boundary between soft and hard strata is in tunnel face,the greater the thickness coefficient of weak strata is,the smaller the stability is.With the increase of the relative thickness coefficient of weak strata,the area of collapse in front of tunnel face is enlarged and the maximum displacement is below the center of the weak strata of tunnel face.The range of stress arch is expanding,and the force transferred to the lower part of tunnel face is greater.Therefore,more attention should be paid to reinforcing the lower part of tunnel face.There is an optimal path for the joint effect of cohesion and internal friction angle on the tunnel face stability,and the reinforcement effect along this path is the most effective.Tunnel face stability decreases with the increase of soil weight,excavation height and the thickness of weak strata.There is an extreme value for the effect of thickness-span ratio on the stability of tunnel face,which can be used as one of the reference conditions for determining the reasonable buried depth of tunnel.Surface surcharge affects the stability of tunnel face only when it is shallow buried.
引文
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[3] SENENT Salvador,JIMENEZ Rafael.A Tunnel Face Failure Mechanism for Layered Ground Considering the Possibility of Partial Collapse[J].Tunnelling and Underground Space Technology,2015,47(3):182-192.
[4] TTHkos,GONG Qiuming,ZHAO Jian.Case Studies of TBM Tunneling Performance in Rock-Soil Interface Mixed Ground[J].Tunnelling and Underground Space Technology,2013,38(4):151-159.
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[8] BROMS B B,BENNERMARK H.Stability of Clay at Vertical Openings[J].Journal of the Soil Mechanics&Foundations Division,1967,93(1):71-94.
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[12]王国富,孙捷城,路林海,等.突变地质界面盾构隧道开挖面极限支护压力研究[J].中国铁道科学,2016,37(6):50-59.(WANG Guofu,SUN Jiecheng,LU Linhai,et al.Study on Limit Support Pressure of Shield Tunnel Excavation Face with Mutational Geological Interface[J].China Railway Science,2016,37(6):50-59.in Chinese)
[13]邱龑,杨新安,徐前卫,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.(QIU Yan,YANG Xinan,XU Qianwei,et al.Analysis on Stability and Instability Risk of Excavation Face of Shield Tunnel in Water Rich Sand Layer[J].China Railway Science,2015,36(6):55-62.in Chinese)
[14]张黎明,郑颖人,王在泉,等.有限元强度折减法在公路隧道中的应用探讨[J].岩土力学,2007,28(1):97-102.(ZHANG Liming,ZHENG Yingren,WANG Zaiquan,et al.Application of Strength Reduction Finite Element Method to Road Tunnels[J].Rock and Soil Mechanics,2007,28(1):97-102.in Chinese)
[15] CHEN W F.Limit Analysis and Soil Plasticity[M].New York:Elsevier Scientific Publishing Company,1975.
[16]吕玺琳,王浩然,黄茂松.盾构隧道开挖面稳定极限理论研究[J].岩土工程学报,2011,33(1):57-62.(LXilin,WANG Haoran,HUANG Maosong.Limit Theoretical Study on Face Stability of Shield Tunnels[J].Chinese Journal of Geotechnical Engineering,2011,33(1):57-62.in Chinese)
[17]童建军.厦门东通道海底随道翔安端砂层地段掌子面稳定性研究[D].成都:西南交通大学,2008.(TONG Jianjun.Study on the Face Stability of the Land Layer at Xiangan End of Eastern Passage of Xiamen Subway Tunnel[D].Chengdu:Southwest Jiaotong University,2008.in Chinese)
[18]台启民.极不稳定隧道围岩超前破坏机制与安全性评价[D].北京:北京交通大学,2016.(TAI Qimin.Failure Mechanism Ahead of Tunnel Face and Safety Assessment of Unstable Tunnel Surrounding Rock[D].Beijing:Beijing Jiaotong University,2016.in Chinese)
[19] CHAMBON P,CORTE J F.Shallow Tunnels in Cohesionless Soil:Stability of Tunnel Face[J].Journal of Geotechnical Engineering,1994,120(7):1148-1165.
[2] GOMES Rui Carrilho,GOUVEIA Fátima,TORCATO Diogo,et al.Seismic Response of Shallow Circular Tunnels in Two-Layered Ground[J].Soil Dynamics and Earthquake Engineering,2015,75(8):37-43.
[3] SENENT Salvador,JIMENEZ Rafael.A Tunnel Face Failure Mechanism for Layered Ground Considering the Possibility of Partial Collapse[J].Tunnelling and Underground Space Technology,2015,47(3):182-192.
[4] TTHkos,GONG Qiuming,ZHAO Jian.Case Studies of TBM Tunneling Performance in Rock-Soil Interface Mixed Ground[J].Tunnelling and Underground Space Technology,2013,38(4):151-159.
[5] NEAUPANE K M,ADHIKARI N R.Prediction of Tunneling-Induced Ground Movement with the Multi-Layer Perceptron[J].Tunnelling and Underground Space Technology,2006,21(2):151-159.
[6] FENG Wenkai,HUANG Runqiu,LI Tianbin.Deformation Analysis of a Soft-Hard Rock Contact Zone Surrounding a Tunnel[J].Tunnelling and Underground Space Technology,2012,32(5):190-197.
[7] DAVIS E H,GUNN M J,MAIR R J,et al.The Stability of Shallow Tunnels and Underground Openings in Cohesive Material[J].Geotechnique,1980,30(4):397-416.
[8] BROMS B B,BENNERMARK H.Stability of Clay at Vertical Openings[J].Journal of the Soil Mechanics&Foundations Division,1967,93(1):71-94.
[9] ANAGNOSTOU G,KOVRI K.The Face Stability of Slurry Shield-Driven Tunnels[J].Tunnelling and Underground Space Technology,1994,9(2):165-174.
[10]刘招伟.城陵矶穿越长江水下软硬不均地层隧道修建技术[J].中国铁道科学,2006,27(3):139-143.(LIU Zhaowei.Construction Technology of Chenglingji Yangtze River Crossing Tunnel in Hard-Soft Heterogeneous Ground[J].China Railway Science,2006,27(3):139-143.in Chinese)
[11]熊良宵,杨林德.隧道开挖面接近地质界面时围岩位移特征及其影响因素分析[J].中国铁道科学,2009,30(1):61-68.(XIONG Liangxiao,YANG Linde.Displacement Characteristics of the Surrounding Rock and the Influencing Factors Analysis When Tunnel Excavating towards the Geological Interface[J].China Railway Science,2009,30(1):61-68.in Chinese)
[12]王国富,孙捷城,路林海,等.突变地质界面盾构隧道开挖面极限支护压力研究[J].中国铁道科学,2016,37(6):50-59.(WANG Guofu,SUN Jiecheng,LU Linhai,et al.Study on Limit Support Pressure of Shield Tunnel Excavation Face with Mutational Geological Interface[J].China Railway Science,2016,37(6):50-59.in Chinese)
[13]邱龑,杨新安,徐前卫,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.(QIU Yan,YANG Xinan,XU Qianwei,et al.Analysis on Stability and Instability Risk of Excavation Face of Shield Tunnel in Water Rich Sand Layer[J].China Railway Science,2015,36(6):55-62.in Chinese)
[14]张黎明,郑颖人,王在泉,等.有限元强度折减法在公路隧道中的应用探讨[J].岩土力学,2007,28(1):97-102.(ZHANG Liming,ZHENG Yingren,WANG Zaiquan,et al.Application of Strength Reduction Finite Element Method to Road Tunnels[J].Rock and Soil Mechanics,2007,28(1):97-102.in Chinese)
[15] CHEN W F.Limit Analysis and Soil Plasticity[M].New York:Elsevier Scientific Publishing Company,1975.
[16]吕玺琳,王浩然,黄茂松.盾构隧道开挖面稳定极限理论研究[J].岩土工程学报,2011,33(1):57-62.(LXilin,WANG Haoran,HUANG Maosong.Limit Theoretical Study on Face Stability of Shield Tunnels[J].Chinese Journal of Geotechnical Engineering,2011,33(1):57-62.in Chinese)
[17]童建军.厦门东通道海底随道翔安端砂层地段掌子面稳定性研究[D].成都:西南交通大学,2008.(TONG Jianjun.Study on the Face Stability of the Land Layer at Xiangan End of Eastern Passage of Xiamen Subway Tunnel[D].Chengdu:Southwest Jiaotong University,2008.in Chinese)
[18]台启民.极不稳定隧道围岩超前破坏机制与安全性评价[D].北京:北京交通大学,2016.(TAI Qimin.Failure Mechanism Ahead of Tunnel Face and Safety Assessment of Unstable Tunnel Surrounding Rock[D].Beijing:Beijing Jiaotong University,2016.in Chinese)
[19] CHAMBON P,CORTE J F.Shallow Tunnels in Cohesionless Soil:Stability of Tunnel Face[J].Journal of Geotechnical Engineering,1994,120(7):1148-1165.