Dayeq refers to the siege works constructed by an attacking army — walls of circumvallation, siege towers, or earthworks built around a city to starve out or assault its defenders. Used in Ezekiel's prophecy against Tyre (Ezekiel 4:2; 17:17; 21:22) and in other siege contexts. The siege of Jerusalem by Babylon, foretold by Ezekiel in vivid enacted prophecy, is the primary context.
The siege works of Babylon against Jerusalem serve as a prophetic picture of divine judgment: when a nation that bears God's name abandons His covenant, He can use even pagan armies as instruments of correction. Yet the same imagery is reversed in hope — the New Jerusalem needs no siege works against it (Revelation 21:25: 'its gates will never be shut'). The city that was besieged and broken becomes the eternal city that cannot be taken. Judgment gives way to glory.