Digging　blasting　is　the　key　to　rock　tunnel　excavation　blasting.　Here,　aiming　at　problems　of　low　utilization　rate　of　cross-section　blasting　boreholes　and　small　footage,　based　on　the　principle　of　ultra-deep　blasting,　a　3-D　model　of　ultra-deep　blasting　was　established　to　analyze　dynamic　resistance　in　blasting　throwing　process,　and　derive　the　mathematical　relation　between　ultra-deep　coefficient　and　hole　depth　under　ultimate　equilibrium　state　using　the　I-D　directional　throwing　balance　relation.　Effects　of　ultra-deep　coefficient　variation　on　digging　blasting　effect　were　analysed　The　smooth　particle　hydrodynamics-finite　element　method　coupled　method　was　used　to　simulate　change　laws　of　groove　cavities　in　different　ultra-　deep　models.　Finally,　through　on-site　tests,　the　ultra-deep　Masting　technology　was　used　to　compare　evaluation　indexes　of　blasting　effects　between　different　ultra-deep　blasting　schemes　and　the　original　scheme.　The　study　showed　that　with　increase　in　ultra-depth　coefficient,　utilization　rate　of　crom-section　blast　hole　exhibits　a　trend　of　firstly　increasing　and　then　decreasing;　when　ultra-depth　coefficient　is　in　the　range　of　0.11　-0.15,　it　obviously　improv　blasting　effect;　when　ultra-depth　coefficient　increases,　the　clamping　action　among　ocks　makes　it　difficult　to　throw　fragmented　rocks,　so　groove　cavity　volume　decreases;　within　ultra-depth　coefficient　range　of　0.　12-0.15,　the　single　cycle　footage　of　rock　roadway　cross-section　can　increase　by　100　mm-150　mm,　and　the　utilization　rate　of　blasting　holes　can　increase　by　4%-6%;　the　precise　matching　of　hole　depth　and　ultra-depth　coefficient　can　not　only　obtain　the　ideal　blasting　effect,　but　also　have　good　economic　benefits.　©　2025　Chinese　Vibration　Engineering　Society.　All　rights　reserved.