The kanji character 坑坑 primarily represents a "pit," "hole," or "mine shaft." It signifies a depression in the ground, often one created for a specific purpose such as mining or excavation. It implies a constructed or naturally occurring hollow or cavity.

・On-yomi (音読み): こう (kō) ・Kun-yomi (訓読み): あな (ana) – hole, pit, cavity

⚫︎炭坑 Translation: coal mine ⚫︎坑道 Translation: tunnel; mine gallery ⚫︎陥 坑《坑》 Translation: a pit; a trap

The kanji character 坑坑 is a phono-semantic compound (形声文字). The left side, 土土 (tsuchi), is the radical and means "earth" or "ground," indicating that the character relates to something found in the earth. The right side is 工工 (kō), which means "work" or "craft." So, it is the earth that involves construction or work to form a hole. The combination suggests a man-made pit, hole, or excavation in the earth, such as a mining pit.