"不均匀沉陷" can be translated into English as "uneven settlement" or "differential settlement".
"Uneven settlement" emphasizes the non-uniformity or irregularity of the settlement.
"Differential settlement" specifically highlights the difference in settlement amounts between different parts of a structure or foundation, which is a more technical and precise term often used in engineering contexts.
Both translations are acceptable, and the choice between them may depend on the specific context and the level of technicality required.