一种显式动力有限元快速积分方法

A new fast integration method for explicit dynamic FEM

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.