Permanent　ground　deformation　hazards,　such　as　fault　displacement,　liquefaction-induced　settlement,　and　landslides,　pose　a　severe　threat　to　the　integrity　of　buried　pipelines.　In　this　study,　three-dimensional　numerical　simulations　are　performed　to　investigate　the　horizontal　lateral　soil-pipeline　interaction　in　medium-dense　sand　and　to　identify　the　failure　mechanisms　of　the　surrounding　sand　for　different　pipeline　depth-diameter　ratios.　The　ultimate　bearing　capacity　of　sand　around　the　pipeline　is　evaluated　for　different　soil　failure　mechanisms.　Moreover,　a　simplified　analytical　model　of　the　soil-pipeline　under　lateral　movement　is　proposed　based　on　the　identified　soil　failure　mechanisms.　Consequently,　an　analytical　solution　for　the　ultimate　bearing　capacity　of　the　soil　under　lateral　motion　of　the　buried　pipeline　is　derived　based　on　the　limit-state　equilibrium.　The　results　obtained　from　the　analytical　solution　indicate　that　at　the　limit　state,　the　soil　around　a　shallowly　buried　pipeline　forms　a　ruptured　surface　extending　to　the　ground　surface　with　a　logarithmic　spiral　failure　surface.　The　lateral　ultimate　bearing　capacity　increases　as　the　pipeline　burial　depth-diameter　ratio　increases　until　it　reaches　a　constant　value　at　a　certain　critical　depth-diameter　ratio.　As　the　pipeline　depth-diameter　ratio　increases,　the　pipeline　displacement　that　causes　shear　failure　of　the　soil　also　gradually　increases.　It　is　demonstrated　that　the　proposed　analytical　solution　well　predicts　the　soil　ultimate　lateral　bearing　capacity　for　pipelines　installed　shallowly　in　medium　and　dense　sand.　Furthermore,　the　ultimate　bearing　capacity　of　pipelines　in　sand　is　evaluated　by　Chinese　and　some　international　codes.　The　disparity　between　results　from　different　codes　is　attributed　to　the　variation　in　empirical　lateral　bearing　capacity　coefficients　used　in　the　respective　codes.　©　2024