一种显式动力有限元快速积分方法
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摘要
我国众多大型地下洞室群位于西南地震频发区,其抗震安全特性值得关注.显式动力有限元时程分析法在实际洞室群工程地震分析中耗时较长,严重制约了该方法的广泛应用.结合显式有限元的积分特点,从有限元积分层面上提出了单、多高斯点分区混合积分方法,以便降低计算量,缩短求解耗时.在计算中,根据计算任务对单元进行积分区域划分,对重点分析的计算区域、边界单元等部位采用八高斯点积分,确保计算精度及人工边界的数值稳定.对其余模型区域采用单高斯点积分,节省计算耗时.采用该方法对某水电站地下厂房洞室围岩进行动力时程计算,速度提高82.4%,取得较好效果.
Seismic safety of underground caverns in Southwest China where earthquake frequently occurring deserves wide attention.Explicit dynamic FEM is effective but time-consuming for time-history seismic analysis of underground caverns that limits its wide engineering application.To cope with this issue,a new hybrid Gauss integration method is proposed.Using the method,the FE model is divided into different calculation regions according to different calculation tasks.For the key calculation regions and boundary elements,the integration method using 8 Gauss points is employed to improve calculation accuracy and stability.For other calculation regions,integration method with single Gauss point is used to enhance the solving speed.The integration methodology is verified by applying explicit dynamic FEM to seismic analysis of underground powerhouse of a hydropower station;and it is shown that the solving time is shortened by 82.4% with accurate simulation results.
Seismic safety of underground caverns in Southwest China where earthquake frequently occurring deserves wide attention.Explicit dynamic FEM is effective but time-consuming for time-history seismic analysis of underground caverns that limits its wide engineering application.To cope with this issue,a new hybrid Gauss integration method is proposed.Using the method,the FE model is divided into different calculation regions according to different calculation tasks.For the key calculation regions and boundary elements,the integration method using 8 Gauss points is employed to improve calculation accuracy and stability.For other calculation regions,integration method with single Gauss point is used to enhance the solving speed.The integration methodology is verified by applying explicit dynamic FEM to seismic analysis of underground powerhouse of a hydropower station;and it is shown that the solving time is shortened by 82.4% with accurate simulation results.
引文
[1]张晓志,谢礼立.采用显式有限元方法求解开放系统动力响应的主要环节和问题[J].地震工程与工程振动,2005,25(3):10-15.
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[6]张志国,肖明,张雨霆,等.大型地下洞室三维弹塑性损伤动力有限元分析[J].岩石力学与工程学报,2010,29(5):982-989.
[2]John O Hallquist.Ls-Dyna Theoretical Manual[S],1998.
[3]刘波,韩彦辉.Flac原理、实例与应用指南[M].北京:人民交通出版社,2005.
[4]张雄,王天舒.计算动力学[M].北京:清华大学出版社,2007.
[5]张志国,肖明,陈俊涛.大型地下洞室地震灾变过程三维动力有限元模拟[J].岩石力学与工程学报,2011,30(3):509-523.
[6]张志国,肖明,张雨霆,等.大型地下洞室三维弹塑性损伤动力有限元分析[J].岩石力学与工程学报,2010,29(5):982-989.
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