flac3d动力分析边界问题，手册上有这么一句：If a stress boundary condition isused during the static solution, a stress boundary condition of opposite sign must also be applied over the same boundary when the quiet boundary is applied for the dynamic phase. This will allow the correct reaction forces to be in place at the boundary for the dynamic calculation.当静力问题采用应力边界时，动力计算时粘性边界怎么设置？？？手册上这句话怎么理解？盼高手指点，不生感激！！！
