全部

1·According to the research, the natural graded gravel is the best backfill material of graded crushed stone, grit, lime stabilized soil and rock chips.

研究表明，在连续级配碎石、砂砾、石灰稳定土、石屑几种回填材料中以自然级配砂砾石为最佳台背回填材料。