The　collision　and　fragmentation　patterns　of　rockfalls　under　the　influence　of　joints　were　studied　through　physical　experiments.　Based　on　indoor　collision　tests,　the　discontinuous　deformation　analysis　(DDA)　parallel　computing　method　was　used　to　simulate　the　impact-collision-fragmentation　process　of　rockfalls.　The　main　focus　is　on　discussing　the　influence　of　the　angle　β　between　the　joint　and　the　slope,　the　connectivity　rate　k　of　the　joint,　and　the　impact　velocity　V　of　the　rockfall　on　its　crushing　characteristics.　The　ratio　η　of　the　surface　area　of　the　rockfall　to　its　initial　surface　area　is　used　as　a　quantitative　measure　of　the　degree　of　fragmentation,　with　a　larger　η　indicating　a　higher　degree　of　fragmentation.　The　research　findings　are　as　follows:　1)　η　increases　with　k;　under　high-velocity　impact　conditions,　the　η　value　at　k　=　0.75　is　1.2　times　that　at　k　=　0.25.　2)　When　k　=　0.25,　η　does　not　vary　significantly　with　β　;　however,　when　k　=　0.50　and　0.75,　η　decreases　as　β　increases.　3)　The　η　value　under　high-speed　impact　(6.8-7.4　m/s)　is　1.5　times　higher　than　that　under　low-speed　conditions　(3.5-4.5　m/s).　4)　As　the　single-joint　connectivity　rate　k　of　the　rockfall　increases　from　0　to　0.75,　the　energy　recovery　coefficient　exhibits　a　decreasing　trend,　with　its　value　reduced　by　1.6　to　1.9　times.　5)　With　the　increase　in　impact　velocity,　the　energy　recovery　coefficient　of　the　rockfall　gradually　increases　with　the　increase　in　joint　angle　β,　up　to　1.6　times.　6)　The　fracture　characteristics　and　degree　of　fragmentation　obtained　through　numerical　simulation　and　indoor　collision　tests　are　basically　the　same.　An　increase　in　the　single-joint　connectivity　rate　and　the　angle　between　the　joint　and　the　slope　surface　affects　stress　propagation　and　alters　the　fracture　characteristics　of　the　specimens.　7)　When　a　multi-jointed　rockfall　is　impacted　and　broken,　the　cracks　do　not　extend　along　the　outline　of　the　joint　setting　and　do　not　intersect　with　joints　far　from　the　center　of　the　rock.　The　velocity　of　the　debris　after　impact　is　slightly　lower　than　that　before　impact.　This　study　has　certain　reference　significance　for　revealing　the　collision　and　fragmentation　patterns　of　rockfalls　under　the　influence　of　natural　joints.　©　2025　Biodiversity　Research　Center　Academia　Sinica.　All　rights　reserved.