短語詞組短語sand soil layer 砂土層blowing sand boundary layer 風沙邊界層sand -layer liquefaction 砂土液化compound sand cushion layer 複郃砂墊層sand mat layer 砂墊層sand filter layer 砂濾層sand cushion layer 砂墊層thin sand powder layer 粉細砂地層 返回 sand layer