Fully　buried　portal　frame-shaped　piles　have　been　widely　used　to　control　and　stabilize　largescale　landslides　or　slopes.　However,　the　working　mechanism　of　portal　frame　piles,　such　as　the　soil-pile　interaction　and　load　transfer　behavior,　is　still　not　fully　understood,　which　has　limited　the　development　of　effective　pile　designs　and　construction.　In　this　study,　a　well-designed　laboratory　model　test　was　conducted　in　a　sandy　soil　slope　with　a　man-made　slip　surface.　Nine　portal　frame　piles　were　installed,　synthetically　considering　the　pile　spacing　between　the　rear　and　front　piles　as　well　as　the　support　condition　of　the　pile　ends.　To　make　the　test　closer　to　reality,　in　addition　to　a　small　thrust　due　to　the　excavation　of　the　slope,　greater　landslide　thrusts　were　imposed　on　the　rear　side　of　the　portal　frame　piles　by　gradually　applying　static　loads　on　the　top　of　the　slope.　It　is　found　that　in　addition　to　a　concentrated　thrust　transferred　via　the　cap　beam,　a　landslide　thrust　accounting　for　30　to　60　%　of　the　landslide　thrust　on　the　rear　pile　was　transmitted　to　the　front　pile　by　the　soil　sandwiched　between　the　rear　and　front　piles,　which　should　not　be　ignored　in　designs.　Meanwhile,　to　evenly　mobilize　the　bearing　capacity　of　both　the　rear　and　front　piles,　the　reasonable　spacing　between　them　should　be　1.0　to　1.5　times　the　diameter　of　the　pile.　The　study　also　shows　that　portal　frame　piles　should　be　embedded　in　a　stable　soil　layer　rather　than　the　bedrock　if　they　can　meet　the　requirements　for　bearing　capacity.　Copyright　©　2022　by　ASTM　International,　100　Barr　Harbor　Drive,　PO　Box　C700,　West　Conshohocken,　PA　19428-2959.