短语词组短语clay central core 粘土心墙clay impervious core 粘土防渗墙clay -core gravel sand dam 砂砾石粘土心墙坝clay central core embankment dam 粘土心墙土石坝inclined clay -core wall 粘土斜墙clay sloping core roch -fill dam 粘土斜心墙堆石坝clay core wall 粘土心墙 返回 clay core