A trench digging machine is being used at the construction site.
We dug a one-meter-deep trench with a trencher.
Standard kanji spelling for a trench digging machine.
Variant spelling without the okurigana り; less common but still used.
Compound of 溝 (みぞ, 'ditch, trench'), 掘り (ほり, the continuative form of 掘る 'to dig'), and 機 (き, 'machine').