破碎围岩浅埋偏压隧道衬砌荷载的计算方法
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摘要
隧道洞口大都会面临围岩破碎、浅埋和偏压等不良地质地形情况,现行规范只给出了偏压隧道衬砌荷载的计算方法。对于破碎围岩浅埋偏压隧道,根据现场情况及实测的衬砌受力和变形特征表明其与规范假定不同,不宜直接利用规范方法。通过工程实例分析及隧道三维数值分析结果提出了浅埋偏压隧道破碎围岩的破坏模式,即隧道开挖后深埋侧岩体滑塌下落挤压支护结构使其向外侧变形,从而外侧支护受到被动土压力。根据提出的破坏模式,将隧道开挖后围岩主要分为滑塌区和被动区,在此基础上利用极限平衡法推导出了衬砌荷载的计算公式。将计算得到的结果与现场实测值对比发现,对于围岩极其破碎且存在较严重偏压的浅埋隧道工程,提出的计算方法比采用规范方法更接近实际情况。
Tunnel portal section mostly faces unfavorable geologic and topographical conditions,such as broken surrounding rock,shallow and unsymmetrical loadings.The current Chinese code for design of road tunnel provides the load calculation method of tunnel under unsymmetrical.However,according to the mechanic and deformation characteristics of the tunnel lining on site,the assumption is not suitable for the shallow tunnel under unsymmetrical loadings in broken surrounding rock.Therefore,through engineering case analysis and results of three-dimensional numerical analysis,the failure mechanism of shallow tunnel under unsymmetrical loadings in broken surrounding rock is presented firstly,that is,deep buried side broken surrounding rocks slump down after excavation and squeeze the lining,which makes the lining deform outward and bear passive earth pressure.Through the failure mechanism,the surrounding rock mainly includes slumping area and passive area.Then the corresponding formulas are deduced based on limit equilibrium theory.Finally,a case study is adopted to verify the feasibility of the new method.It is show that the new method is more reasonable than the method of current code.
Tunnel portal section mostly faces unfavorable geologic and topographical conditions,such as broken surrounding rock,shallow and unsymmetrical loadings.The current Chinese code for design of road tunnel provides the load calculation method of tunnel under unsymmetrical.However,according to the mechanic and deformation characteristics of the tunnel lining on site,the assumption is not suitable for the shallow tunnel under unsymmetrical loadings in broken surrounding rock.Therefore,through engineering case analysis and results of three-dimensional numerical analysis,the failure mechanism of shallow tunnel under unsymmetrical loadings in broken surrounding rock is presented firstly,that is,deep buried side broken surrounding rocks slump down after excavation and squeeze the lining,which makes the lining deform outward and bear passive earth pressure.Through the failure mechanism,the surrounding rock mainly includes slumping area and passive area.Then the corresponding formulas are deduced based on limit equilibrium theory.Finally,a case study is adopted to verify the feasibility of the new method.It is show that the new method is more reasonable than the method of current code.
引文
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[11]杨峰,阳军生.浅埋隧道围岩压力确定的极限分析方法[J].工程力学,2008,25(7):179-184.YANG FENG,YANG JUN-SHENG.Limit analysis method for determination of earth pressure on shallow tunnel[J].Engineering Mechanics,2008,25(7):179-184.
[12]杨小礼,王作伟.非线性破坏准则下浅埋隧道围岩压力的极限分析[J].中南大学学报:自然科学版,2010,41(3):1090-1095.YANG XIAO-LI,WANG ZUO-WEI.Limit analysis of earth pressure on shallow tunnel using nonlinear failure criterion[J].J.Cent.South Univ:Science and Technology,2010,41(1):299-302.
[13]李亮,郭乃正,傅鹤林,等.破碎围岩中连拱隧道载荷计算理论解[J].中国铁道科学,2004,25(4):50-54.LI LIANG,GUO NAI-ZHENG,FU HE-LIN,et al ed.Theoretical load solution to chain tunnel inside broken surrounding rock[J].China Railway Science,2004,25(4):50-54.
[14]朱正国,刘志春,孙明磊,等.偏压连拱隧道围岩压力及结构计算[J].辽宁工程技术大学学报:自然科学版,2010,29(1):75-78.ZHU ZHENG-GUO,LIU ZHI-CHUN,SUN MING-LEI,et al ed.Calculation of surrounding rock pressure and structure of multi-arch tunnel under unsymmetrical pressure[J].Journal of Liaoning Technical University:Natural Science,2010,29(1):75-78.
[15]杨小礼,黄波,王作伟.水平地震力作用下浅埋偏压隧道松动围岩压力的研究[J].中南大学学报:自然科学版,2010,41(3):1090-1095.YANG XIAO-LI,HUANG BO,WANG ZUO-WEI.Numerical simulation of construction sequence for shallow embedded bias tunnels with small clear distance[J].J.Cent.South Univ:Science and Technology,2010,41(3):1090-1095.
[16]王成华.土力学原理[M].天津:天津大学出版社,2002.
[2]王明年,郭军,罗禄森,等.高速铁路大断面深埋黄土隧道围岩压力计算方法[J].中国铁道科学,2009,30(5):53-58.WANG MING-NIAN,GUO Jun,LUO Lu-se,et al ed.Calculation method for the surrounding rock pressure of deep buried large sectional loess tunnel of high-speed railway[J].China Railway Science,2009,30(5):53-58.
[3]JIANG Y,YONEDA H,TANABASHI Y.Theoretical estima-tion of loosing pressure on tunnels in soft rocks[J].Tunnelling and Underground Space Technology,2001,16:99-105.
[4]BROWN E T,BRAY J W,LADANYI B,et al.Ground response curves for rock tunnels[J].Journal of Geotechnical Engineering,1983,109:15-39.
[5]LEE C J,WU B R,CHEN H T.Tunnel stability and arc-hing effects during tunneling in soft clayey soil[J].Tunnelling and Underground Space Technology,2006(21):119-132.
[6]王德荣,甄树新,汪新红,等.深部坑道围岩压力与变形分析[J].岩土力学,2007,28(3):570-576.WANG DE-RONG,ZENG SHU-XIN,WANG XIN-HONG,et al.Analysis of pressure and deformation of wall rock near deep tunnel[J].Rock and Soil Mechanics,2007,28(3):570-576.
[7]邵生俊,邓国华.原状黄土的结构性强度特性及其在黄土隧道围岩压力分析中的应用[J].土木工程学报,2008,41(11):93-98.SHAO SHENG-JUN,DENG GUO-HUA.The strength characteristics of loess with different structures and its application in analyzing the earth pressure on loess tunnel[J].China Civil EngineeringJournal,2008,41(11):93-98.
[8]YANG XIAO-LI.Upper bound limit analysis of active earth pressure with different fracture surface and nonlinear yield criterion[J].Theoretical and Applied Fracture Mechanics,2007,47(1):46-56.
[9]DAVIS E H,GUNN M J,MAIR R J.The stability of shallow tunnel and underground openings in cohesive material[J].Geotechnique,1980,30(4):397-416.
[10]LECA E,DORMIEUX L.Upper and lower bound solutions for the face stability of shallow circular tunnels in frictional material[J].Geotechnique,1990,40(4):581-606.
[11]杨峰,阳军生.浅埋隧道围岩压力确定的极限分析方法[J].工程力学,2008,25(7):179-184.YANG FENG,YANG JUN-SHENG.Limit analysis method for determination of earth pressure on shallow tunnel[J].Engineering Mechanics,2008,25(7):179-184.
[12]杨小礼,王作伟.非线性破坏准则下浅埋隧道围岩压力的极限分析[J].中南大学学报:自然科学版,2010,41(3):1090-1095.YANG XIAO-LI,WANG ZUO-WEI.Limit analysis of earth pressure on shallow tunnel using nonlinear failure criterion[J].J.Cent.South Univ:Science and Technology,2010,41(1):299-302.
[13]李亮,郭乃正,傅鹤林,等.破碎围岩中连拱隧道载荷计算理论解[J].中国铁道科学,2004,25(4):50-54.LI LIANG,GUO NAI-ZHENG,FU HE-LIN,et al ed.Theoretical load solution to chain tunnel inside broken surrounding rock[J].China Railway Science,2004,25(4):50-54.
[14]朱正国,刘志春,孙明磊,等.偏压连拱隧道围岩压力及结构计算[J].辽宁工程技术大学学报:自然科学版,2010,29(1):75-78.ZHU ZHENG-GUO,LIU ZHI-CHUN,SUN MING-LEI,et al ed.Calculation of surrounding rock pressure and structure of multi-arch tunnel under unsymmetrical pressure[J].Journal of Liaoning Technical University:Natural Science,2010,29(1):75-78.
[15]杨小礼,黄波,王作伟.水平地震力作用下浅埋偏压隧道松动围岩压力的研究[J].中南大学学报:自然科学版,2010,41(3):1090-1095.YANG XIAO-LI,HUANG BO,WANG ZUO-WEI.Numerical simulation of construction sequence for shallow embedded bias tunnels with small clear distance[J].J.Cent.South Univ:Science and Technology,2010,41(3):1090-1095.
[16]王成华.土力学原理[M].天津:天津大学出版社,2002.
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