sub-excavation

Noun

An excavation underneath something, or the excavation of a subgrade

Japanese Meaning

何かの下部、または下地となる層の掘削作業

The engineer ordered a controlled sub-excavation under the old foundation to reach the required subgrade level.

技術者は所定の路盤高に達するため、老朽化した基礎の下で慎重に下部掘削を行うよう指示した。

Sense（1）

An excavation underneath something, or the excavation of a subgrade

We were grading the road and found a soft spot where we did a sub-excavation.

sub-excavations

（ plural ）