The　active　earth　pressure　of　earth-retaining　structures　(ERSs)　is　highly　dependent　on　rainfall　infiltration.　In　prior　studies,　ERS　stability　was　primarily　explored　based　on　backfills　under　unsaturated　steady　flows　or　those　that　were　saturated　or　dry　while　neglecting　the　time-dependent　properties　of　the　rainfall　infiltration　procedure.　Accordingly,　this　study　assessed　the　stability　of　a　three-dimensional　(3D)　unsaturated　ERS　under　diverse　modes　of　rainfall　infiltration　by　exploiting　the　upper　bound　theorem　of　limit　analysis.　A　modified　Green-Ampt　model　was　adopted　to　consider　the　development　of　the　wetting　front;　thereafter,　an　energy　equilibrium　equation　was　built　to　analytically　derive　the　active　earth　pressure.　The　effects　of　the　wall　friction　angle,　ERS　3D　geometrical　characteristics,　rainfall　infiltration　intensity　and　duration,　and　rainfall　patterns　on　the　active　earth　pressure　coefficient　were　investigated.　According　to　the　results,　the　wall　friction　angle　and　3D　geometrical　characteristics　lead　to　a　smaller　active　earth　pressure　and　a　superior　stability　state.　The　matric　suction　is　a　direct　determinant　of　the　active　earth　pressure　and　stability　of　the　ERS;　these　exert　major　effects　on　the　infiltration　rate　of　rainfall　into　the　soil.　Furthermore,　the　rainfall　pattern　and　intensity　also　have　significant　impacts　on　the　active　earth　pressure　and　the　development　of　the　wetting　front.