求翻译：砂石垫层应在最佳含水率下分层振压密实,每层厚度200mm,压实系数>0.97,处理后砂石垫层的承载力特征值fak=180KPa。是什么意思？

Gravel cushion pressure should be at the optimum moisture content under vibration compacting, each layer thickness 200mm, >0.97 the compaction coefficient, gravel cushion bearing capacity characteristic value after processing fak=180KPa.