Research　purposes:　Semi-integral　abutment　jointless　bridge　(SAJB)　is　a　new　type　of　bridge　structure.　Due　to　the　rigid　connection　of　main　girder　and　abutment,　the　main　girder　will　induce　the　bridge　abutment　to　undergo　reciprocating　displacement　along　the　longitudinal　bridge　direction,　which　results　the　changes　of　soil　resistance　behind　the　abutment　under　the　long-term　effects　of　diurnal　and　seasonal　ambient　temperature.　In　order　to　study　the　distribution　law　of　the　soil　resistance　behind　the　abutment　and　the　influence　of　the　medium　long-term　ambient　temperature　on　it,　a　quasi-static　test　of　the　semi-integral　abutment-soil　interaction　was　carried　out　under　medium　and　long-term　ambient　temperature.　Research　conclusions:(1)　The　soil　resistance　with　the　ambient　temperature　rises　rapidly　in　the　1st　to　6th　middle　period　(the　first　warming　interval　from　spring　to　summer),　then　decrease　in　the　6th　to　16th　middle　period　(the　period　from　summer　to　summer).　In　the　16th　to　20th　middle　period　(the　second　warming　interval　from　winter　to　spring),　it　starts　to　increase　again,　but　the　increase　rate　is　slightly　slow　compared　to　the　first　warming　interval.　(2)　The　soil　resistance　along　the　buried　depth　increases　firstly　until　reaching　the　maximum　at　the　buried　depth　of　0.8h,　and　then　decreases　under　the　medium　long-term　ambient　temperature.　(3)　The　law　of　soil　resistance　along　longitudinal　direction　in　each　period　is　that　in　the　area　near　the　abutment,　the　soil　resistance　decreases　rapidly;　while　in　the　area　far　away　from　the　abutment,　the　soil　resistance　decreases　slowly　to　0　at　the　position　1.0h　away　from　the　abutment.　(4)　After　a　large　period　of　ambient　temperature,　the　soil　resistance　behind　the　abutment　has　a　significant　cumulative　increasing　effect,　and　its　cumulative　effect　has　a　strong　correlation　with　the　longitudinal　position　and　vertical　depth　of　the　soil.　(5)　The　research　results　can　provide　references　for　the　design　of　semi-integral　bridges　and　the　formulation　of　related　specifications.　©　2022,　Editorial　Department　of　Journal　of　Railway　Engineering　Society.　All　right　reserved.