含节理隧道洞口段地震动力放大效应研究
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摘要
汶川大地震造成都江堰至汶川公路距震中较近的区域多座隧道严重受损,其中隧道洞口段的震害尤为严重。与隧道其他部位不同,洞口段在地震过程中具有与地面结构类似的动力放大效应。通过采用三维离散单元计算程序,研究了含节理隧道洞口段仰坡和衬砌结构的动力放大效应,并与汶川地震隧道实际震害做比较。结果表明:较低刚度的结构面对地震波造成较大的衰减。结构面刚度小于1.5GPa/m时,其对地震波的衰减作用大于仰坡动力放大效应。仰坡坡面与结构面交汇处动力放大效应明显。当结构面刚度等于或大于岩体刚度时,其对地震波的衰减作用不明显。仰坡高度和倾角增大,动力放大效应越明显,且仰坡高度较倾角的动力放大效应明显。所得结论对隧道工程抗减震的研究具有参考意义。
The great Wenchuan Earthquake took place in western Sichuan Province on May 12th,2008. Many tunnels on the highway from Dujiangyan to Wenchuan were damaged severely due to the site located near the epicenter. The seismic damage of tunnel portal was more obvious and grievous than other parts of the tunnel. The tunnel portal demonstrates similar dynamic amplification effect to normal ground structures. Based on the on-site investigation and research,data collection and analysis,the three dimension distinct element numerical analyses were conducted to investigate the dynamic amplification effect of front slope and lining of jointed tunnel portal. The results show that the lower stiffness of structural plane causes the more attenuation of seismic wave. The attenuation effect of structural plane will exceed the dynamic amplification effect when the stiffness of structural plane is lower than 1. 5GPa / m. The dynamic amplification effect is quite evident at the junction of front slope plane and structural plane. The attenuation of seismic wave will become obscure when the stiffness of structural plane is equal or greater than the stiffness of rock. As the height and angle of front slope increase gradually,the dynamic amplification effect becomes apparent. Moreover,the effect caused by the height is more obvious than by angle. All these factors have important implications for aseismic and shock-absorbing technologies of tunnel engineering.
The great Wenchuan Earthquake took place in western Sichuan Province on May 12th,2008. Many tunnels on the highway from Dujiangyan to Wenchuan were damaged severely due to the site located near the epicenter. The seismic damage of tunnel portal was more obvious and grievous than other parts of the tunnel. The tunnel portal demonstrates similar dynamic amplification effect to normal ground structures. Based on the on-site investigation and research,data collection and analysis,the three dimension distinct element numerical analyses were conducted to investigate the dynamic amplification effect of front slope and lining of jointed tunnel portal. The results show that the lower stiffness of structural plane causes the more attenuation of seismic wave. The attenuation effect of structural plane will exceed the dynamic amplification effect when the stiffness of structural plane is lower than 1. 5GPa / m. The dynamic amplification effect is quite evident at the junction of front slope plane and structural plane. The attenuation of seismic wave will become obscure when the stiffness of structural plane is equal or greater than the stiffness of rock. As the height and angle of front slope increase gradually,the dynamic amplification effect becomes apparent. Moreover,the effect caused by the height is more obvious than by angle. All these factors have important implications for aseismic and shock-absorbing technologies of tunnel engineering.
引文
[1]四川省交通厅公路规划勘察设计研究院.国道317、213线都江堰至汶川公路高速路段地震灾后恢复重建方案设计汇报材料[R].成都:四川省交通厅公路规划勘察设计研究院,2008
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[4]杨绪波.大型岩质边坡开挖的岩体结构效应研究[D].成都:成都理工大学,2005(Yang Xubo.Study on the rock mass structure effect of large rock slope during excavation[D].Chengdu:Chengdu University of Technology,2005(in Chinese))
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[8]陶振宇,潘别桐.岩石力学原理与方法[M].武汉:中国地质大学出版社,1991
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[2]Pekau O A.Application of distinct element method in dynamic analysis of high rock slopes and blocky structures[J].Soil Dynamics and Earthquake Engineering,1997,16:386-387
[3]刘亚群.动荷载作用下层状结构岩体边坡变形破坏机理与安全研究[D].武汉:中国科学院武汉岩土力学研究所,2009(Liu Yaqun.Study on the failure mechanism and safety of layered rock slopes subjected to dynamic loads[D].Wuhan:Wuhan Institute of Rock and soil Mechanics,Chinese Academy of Sciences,2009(in Chinese))
[4]杨绪波.大型岩质边坡开挖的岩体结构效应研究[D].成都:成都理工大学,2005(Yang Xubo.Study on the rock mass structure effect of large rock slope during excavation[D].Chengdu:Chengdu University of Technology,2005(in Chinese))
[5]Barton N,Bandis S.Review of predictive capabilities of JRC-JCS mode in engineering practice[C]//Rock Joints Rotterdam:A.A.Balkema,1990:603-610
[6]李兆霞.损伤力学及其应用[M].北京:科学出版社,2002
[7]李同录,罗世毅,何剑,等.节理岩体力学参数的选取与应用[J].岩石力学与工程学报,2004,23(13):2182-2186(Li Tonglu,Luo Shiyi,He Jian,et al.Determination and application of mechanical parameters for jointed rock masses[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(13):2182-2186(in Chinese))
[8]陶振宇,潘别桐.岩石力学原理与方法[M].武汉:中国地质大学出版社,1991
[9]王峥峥,张哲,高波,等.山岭隧道洞口震害因素分析与抗震风险模糊综合评价[J],中南大学学报:自然科学版,2012,43(3):1122-1130(Wang Zhengzheng,Zhang Zhe,Gao Bo,et al.Factors of seismic damage and fuzzy synthetic evaluation on seismic risk of mountain tunnel portals[J].Journal of Central South University:Science and Technology Edition,2012,43(3):1122-1130(in Chinese))
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