In　practical　engineering,　sand　fill　or　sediments　subjected　to　cyclic　loadings　at　varying　frequencies　due　to　earthquakes,　traffic,　and　waves　may　cause　complex　soil　responses.　To　investigate　the　effect　of　loading　frequency　on　the　cyclic　behaviour　of　saturated　sand,　a　series　of　undrained　cyclic　torsional　shear　tests　covering　a　wide　range　of　loading　frequencies　were　conducted　on　Fujian　sand.　The　excess　pore　water　pressure　(EPWP)　in　saturated　sand　can　be　divided　into　two　components:　residual　and　transient.　Special　focus　was　on　the　effect　of　loading　frequency　on　the　development　of　residual　EPWP,　transient　EPWP,　and　shear　strain　amplitude.　The　key　finding　demonstrates　that　the　loading　frequency　has　a　considerable　effect　on　the　association　between　the　double　amplitude　of　transient　EPWP　and　shear　strain　amplitude.　Based　on　the　test　data,　a　threshold　strain　is　proposed　that　can　be　used　to　predict　the　onset　of　shear　dilatancy　in　saturated　sand.　The　liquefaction　strength　in　the　cyclic　torsional　shear　tests　was　also　investigated　and　was　found　to　be　significantly　influenced　by　the　loading　frequency.　The　cyclic　resistance　ratio　(CRR15)　of　saturated　sand　shows　an　increasing　trend　with　the　increase　in　loading　frequency.　©　2023