18.84×2÷3=12.56立方米，12.56×1.8=22.608
1/3*18.84*2*1.8=22.608吨
18.84×2÷3×1.8
v=1/3sh =3/1×18.84×2 =6.28×2 =12.56(平方米)12.56×1.8=22.608(吨)答:这堆沙子重22.608吨。
