改进振动法在地下工程动力时程计算中的应用

摘要

地下工程受到周围土体的约束作用,其动力反映与地面工程有所区别,如将源于地面工程的振动法用于地下工程的动力时程计算分析,需要进行相应的改进.文章通过计算分析发现,振动法用于地下工程动力时程计算时,在计算模型边界条件和波动传播时间效应方面不能反映波动对地下工程作用的实质；通过对比分析,在这两个方面对常规振动法进行了改进；提出了适用于地下工程动力时程计算的改进振动法.该方法的计算模型采用左右两侧粘弹性底部固定的人工边界条件,波动输入采用能够反映波动传播时间效应的分层加速度动态输入法,其计算分析结果与理论解吻合较好,适用于地下工程的动力时程计算分析.%Underground works are restricted by the surrounding soil masses and their dynamic reflection is different from that in surface engineering.If the vibration method for surface engineering is adopted for time-history analysis and calculations in underground works,corresponding improvements must be made as it cannot reflect the essential wave effect on underground works with respect to the boundary conditions of the calculation model and the time effect of wave propagation.By means of contrastive analysis,an improvement is made regarding the conventional vibration method.As for the improved vibration method for the dynamic time-history calculation of underground works,the calculation model uses the artificial boundary condition of two viscoelastic sides with fixed constraint bottoms as well as the dynamic layered acceleration for wave input.The calculation results agree with the theoretical ones very well and demonstrate the capability of the dynamic time-history calculation for underground works.