人工砂砂垫层
artificial aggregate cushion
砂垫层渗透性
permeability of sand cushion
渠床砂砾石料垫层
grit and gravel in the channel bed
砂石垫层
sand-gravel cushion
Sandy stone bedding course
水泥稳定砂砾垫层
cement stabilizing gravel-sand cushion course
饱和动态含水砂层
Saturated Dynamic Water -bearing Sand