落石冲击下拱形明洞结构受力的模型试验研究
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摘要
为研究落石冲击下拱形明洞结构的受力特点,通过改变落石质量及回填土厚度,利用1∶30缩尺模型试验分析了结构落石冲击所在断面不同部位的横向应变、轴力及弯矩等内力响应最大峰值的大小及分布特征,对各内力最大峰值随回填土厚度的变化趋势进行了分析,最后利用结构变形、弯矩及轴力图,对落石冲击下有回填土拱形明洞结构受力模式进行了总结.研究结果表明:拱顶部位力学响应最显著,拱肩次之,拱腰及仰拱最小;结构受力形态可描述为拱顶部位轴向受拉、拱肩及以下部位为轴向受压的力学模式;与静力学分析隧道或明洞衬砌结构的荷载-结构模式不同,现行隧道设计规范中按素混凝土偏心受压构件对拱顶结构进行安全检算的方法并不适用于落石冲击工况;回填土厚度的增大有利于结构拱顶、拱肩及仰拱结构的受力,但对拱腰部位影响复杂,在设计时需结合落石规模、边墙形式及回填方式等进行具体分析.
In order to study the stress characteristics of the arch-shaped open tunnel structure under rockfall impaction,the magnitude and distribution characteristics of crosswise strain,axial force and moment in different parts of the impaction cross-section of the structure were analysed by a 1∶30 reduced scale model test, with changes of the rockfall mass and the backfill thickness. The trend of maximum internal force peak with backfill thickness was also analysed. Finally,the stress pattern of arched open tunnel structure covered with backfill under rockfall impaction was summarized,in terms of the deformation,moment and axial force of the structure. The results indicate that the mechanical response of the vault is the most significant, followed by the spandrel,inverted arch and the hance. The stress pattern of the structure for the vault is axial tension,and for the spandrel and the lower part is axial compression.This is different from the load-structure mode of the static analysis liningstructure of the tunnel or the open tunnel. Hence safety check and computation of the vault structure cannot be carried out according to the eccentric compression component of plain concrete in the tunnel design code,and other solutions should be devised. The increase of backfill thickness is beneficial to the structure of vault,spandrel and inverted arch,but is not necessarily good for hance,and it needs to be analysed by combining the size of rockfall with the form of side wall and backfill way in the design.
In order to study the stress characteristics of the arch-shaped open tunnel structure under rockfall impaction,the magnitude and distribution characteristics of crosswise strain,axial force and moment in different parts of the impaction cross-section of the structure were analysed by a 1∶30 reduced scale model test, with changes of the rockfall mass and the backfill thickness. The trend of maximum internal force peak with backfill thickness was also analysed. Finally,the stress pattern of arched open tunnel structure covered with backfill under rockfall impaction was summarized,in terms of the deformation,moment and axial force of the structure. The results indicate that the mechanical response of the vault is the most significant, followed by the spandrel,inverted arch and the hance. The stress pattern of the structure for the vault is axial tension,and for the spandrel and the lower part is axial compression.This is different from the load-structure mode of the static analysis liningstructure of the tunnel or the open tunnel. Hence safety check and computation of the vault structure cannot be carried out according to the eccentric compression component of plain concrete in the tunnel design code,and other solutions should be devised. The increase of backfill thickness is beneficial to the structure of vault,spandrel and inverted arch,but is not necessarily good for hance,and it needs to be analysed by combining the size of rockfall with the form of side wall and backfill way in the design.
引文
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[16]王玉锁,王涛,周良,等.跨中受落石冲击的拱形护桥明洞力学响应[J].隧道建设,2018,38(1):22-32.WANG Yuosuo,Wang Tao,ZHOU Liang,et al.Mechanical responses of arched protection shed of bridge under rock-fall impaction on midspan of rooftop[J].Tunnel Construction,2018,38(1):22-32.
[17]王玉锁,徐铭,王涛,等.落石冲击下无回填土拱形明洞结构可靠度设计[J].西南交通大学学报,2017,52(6):1097-1103.WANG Yuosuo,XU Ming,Wang Tao,et al.Structural reliability design of non-backfilling arch open tunnel structure under under rock-fall impaction[J].Journal of Southwest Jiaotong University,2017,52(6):1097-1103.
[18]冯高飞.落石冲击下拱形明洞结构概率可靠性研究[D].成都:西南交通大学,2017.
[19]KAWAHARA S,MURO T.Effects of dry density and thickness of sandy soil on impact response due to rockfall[J].Journal of Terramechanics,2006,43:329-340.
[20]LABIOUSE V,DESCOEUDRES F,MONTANI S.Experimental study of rock sheds impacted by rock blocks[J].Structural Engineering International,1996,3(1):171-175.
[2]国家铁路局.铁路隧道设计规范:TB10003-2016[S].北京:中国铁道出版社,2017.
[3]中华人民共和国交通部.公路隧道设计规范:JTGD70-2004[S].北京:人民交通出版社,2004.
[4]王玉锁,周良,李正辉,等.落石冲击下单压式拱形明洞的力学响应[J].西南交通大学学报,2017,52(3):505-515.WANG Yuosuo,ZHOU Liang,LI Zhenghui,et al.Mechanical responses of single-pressure arch-shaped open tunnel structure under rockfall impaction[J].Journal of Southwest Jiaotong University,2017,52(3):505-515.
[5]王玉锁,周良,王涛,等.落石冲击下单压式拱形明洞的回填方式[J].中国铁道科学,2018,39(2):71-79.WANG Yuosuo,ZHOU Liang,Wang Tao,et al.The backfill method of single-pressure arch-shaped open tunnel structure under rockfall impaction[J].China Railway Science,2018,39(2):71-79.
[6]WANG Yusuo,TANG Jianhui,YAN Tao,et al.Model test investigation of rock-fall impaction to cutand-cover tunnel arch structure[J].Applied Mechanics and Materials,2011(90/91/92/93):2492-2499.
[7]唐建辉.落石冲击对隧道明洞结构的影响研究[D].成都:西南交通大学,2013.
[8]王爽,周晓军,罗福君,等.拱形棚洞受落石冲击的模型试验研究[J].振动与冲击,2017,36(12):215-222.WANG Shuang,ZHOU Xiaojun,LUO Funjun,et al.An experimental study on the performance of an arch shaped shed tunnel due to the impact of rockfall[J].Journal of Vibration and Shock,2017,36(12):215-222.
[9]李正辉.落石冲击下拱形明洞落石冲击荷载及荷载效应研究[D].成都:西南交通大学,2017.
[10]汪精河,周晓军,王爽,等.落石冲击下隧道明洞耗能措施研究[J].公路交通科技,2015,32(9):103-108.WANG Jinghe,ZHOU Xiaojun,WANG Shuang,et al.Study on energy dissipation measures for open cut tunnel under rockfall impact[J].Journal of Highway and Transportation Research and Development,2015,32(9):103-108.
[11]张群利,王全才,吴清,等.不同结构类型棚洞的抗冲击性能研究[J].振动与冲击,2015,34(3):72-76.ZHANG Qunli,WANG Quancai,WU Qing,et al.Anti-impact performances of different kinds of shedtunnel structures[J].Journal of Vibration and Shock,2015,34(3):72-76.
[12]冯科.山岭隧道高陡边坡防落石棚洞结构形式研究[D].成都:西南交通大学,2013.
[13]裴向军,刘洋,王东坡.滚石冲击棚洞砂土垫层耗能缓冲机理研究[J].四川大学学报(工程科学版),2016,48(1):15-22.PEI Xiangjun,LIU Yang,WANG Dongpo.Study on the energy dissipation of sandy soil cushions on the rock-shed under rockfall impact load[J].Journal of Sichuan University(Engineering Science Edition),2016,48(1):15-22.
[14]王东坡,何思明,李新坡,等.冲击荷载下EPS垫层棚洞耗能减震作用研究[J].四川大学学报(工程科学版),2012,44(6):102-107.WANG Dongpo,HE Siming,LI Xinpo,et al.Study on the dissipating effects of shed with EPS cushion under impact load[J].Journal of Sichuan University(Engineering Science Edition),2012,44(6):102-107.
[15]熊磊.落石冲击作用下棚洞顶缓冲垫层优化设置研究[D].重庆:重庆交通大学,2016.
[16]王玉锁,王涛,周良,等.跨中受落石冲击的拱形护桥明洞力学响应[J].隧道建设,2018,38(1):22-32.WANG Yuosuo,Wang Tao,ZHOU Liang,et al.Mechanical responses of arched protection shed of bridge under rock-fall impaction on midspan of rooftop[J].Tunnel Construction,2018,38(1):22-32.
[17]王玉锁,徐铭,王涛,等.落石冲击下无回填土拱形明洞结构可靠度设计[J].西南交通大学学报,2017,52(6):1097-1103.WANG Yuosuo,XU Ming,Wang Tao,et al.Structural reliability design of non-backfilling arch open tunnel structure under under rock-fall impaction[J].Journal of Southwest Jiaotong University,2017,52(6):1097-1103.
[18]冯高飞.落石冲击下拱形明洞结构概率可靠性研究[D].成都:西南交通大学,2017.
[19]KAWAHARA S,MURO T.Effects of dry density and thickness of sandy soil on impact response due to rockfall[J].Journal of Terramechanics,2006,43:329-340.
[20]LABIOUSE V,DESCOEUDRES F,MONTANI S.Experimental study of rock sheds impacted by rock blocks[J].Structural Engineering International,1996,3(1):171-175.
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