竖向地震荷载下人字批顶结构石窟的稳定性分析
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摘要
我国部分石窟的空间建造采用了人字批顶形式,体现了中国传统建筑形式与佛教石窟建造形式上的融合。选取莫高窟典型的人字批顶结构的254号石窟作为研究对象,建立了三维的石窟计算模型,考虑了竖向地震荷载作用,通过输入不同地震加速度时程,计算了4种模型情况下石窟岩体的拉应力分布情况。结果表明,石窟的人字批顶处易形成较大拉应力区,易遭受地震破坏;石窟中心塔柱可以有效地提高所在石窟岩体的抗震能力,但对下部窟体的上部岩体会产生应力集中,是窟体防护加固的重点部位。同时,对于洞窟密集而又分上下几层的石窟群,在抗震防护中应充分考虑竖向地震荷载的作用。
Some of the Chinese grottos adopted a gable roof,which is a fusion of Chinese architecture tradition and that of Buddhism.In this paper,using No.254 grotto with gable roof as an example,3D numerical model of the grotto is established and its analysis is done incorporating consideration of vertical ground motion effect and different parameters of time history of ground motion.Working cases of four 3D models are calculated to get tensile stress distribution in rockmass.The results show that the top of the gable roof endures strongest tensile stress and is relatively vulnerable under effect of strong earthquake.Although central pillar can improve seismic resistance of rock mass of grottos,it also causes stress concentration in rocks around both ends,where is the key spot for seismic reinforcement.For close grottos arranged in tiers the effect of vertical seismic loads is an important factor,which should be included for seismic safety of grottos.
Some of the Chinese grottos adopted a gable roof,which is a fusion of Chinese architecture tradition and that of Buddhism.In this paper,using No.254 grotto with gable roof as an example,3D numerical model of the grotto is established and its analysis is done incorporating consideration of vertical ground motion effect and different parameters of time history of ground motion.Working cases of four 3D models are calculated to get tensile stress distribution in rockmass.The results show that the top of the gable roof endures strongest tensile stress and is relatively vulnerable under effect of strong earthquake.Although central pillar can improve seismic resistance of rock mass of grottos,it also causes stress concentration in rocks around both ends,where is the key spot for seismic reinforcement.For close grottos arranged in tiers the effect of vertical seismic loads is an important factor,which should be included for seismic safety of grottos.
引文
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[2]白世伟,林鲁生,徐邦树.凤岗隧洞三维非线性仿真模拟[J].岩土力学,2002,23(6):673-677.
[3]刘汉龙,费康,高玉峰.边坡地震稳定性时程分析方法[J].岩土力学,2003,24(4):553-560.
[4]陈卫忠,朱维申,王宝林,等.节理岩体中洞室围岩大变形数值模拟及模型试验研究[J].岩石力学与工程学报,1998,17(3):223-229.
[5]石玉成,付长华,王兰民.石窟围岩地震变形破坏机制的数值模拟分析[J].岩土力学,2006,27(4):543-548.
[6]秋仁东,石玉成,徐舜华,等.预应力锚索加固石窟岩体的地震动力响应研究[J].西北地震学报,2007,29(1):49-53.
[7]王旭东,张明泉,张虎元,等.敦煌莫高窟洞窟围岩的工程特性[J].岩石力学与工程学报,2000,19(6):756-761.
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