A　cantilever　retaining　wall　with　a　long　relief　shelf　(CRW-LRS)　is　a　particular　type　of　retaining　wall,　but　no　studies　have　yet　reported　on　rotation　about　the　top　of　this　type　of　retaining　wall.　This　work　studied　failure　mechanisms　in　semi-infinite　non-cohesive　soils　in　rotation　about　the　top　using　the　finite　element　elastoplastic　analysis　method　(FEEA).　By　considering　the　influence　of　both　the　relief　shelf　and　rotational　stress　from　the　soil,　a　formula　for　calculating　the　active　earth　pressure　(E-a)　was　developed　using　the　horizontal　differential　layer　limit　analysis　method.　Four　different　parameters　were　studied,　i.e.,　unloading　plate＇s　geometric　conditions,　heel　length　and　the　internal　friction　angle　of　the　backfill,　in　terms　of　their　influence　on　the　E-a　distribution,　resultant　force　etc.　The　lowest　E-a　was　found　when　the　relief　shelf＇　relative　position　m　=　0.4.