The　strainburst　observed　in　laboratory　model　test,　where　a　cubic　rock　sample　with　an　opening　is　compressed　until　a　strainburst　is　induced,　is　generally　triggered　by　the　loading　stress.　In　contrast,　in　real-world　engineering　contexts,　such　strainbursts　are　triggered　by　tunnel　excavation,　which　corresponds　to　the　effect　of　unloading　stress.　This　paper　aims　to　study　the　similar　and　different　strainburst　mechanisms　triggered　by　loading　and　unloading　effects.　Firstly,　the　PD　method　incorporating　the　in-situ　stress　into　the　its　constitutive　relationship　is　proposed　for　computational　efficiency.　Secondly,　the　PD　strainburst　model,　which　can　distinguish　the　crack　propagation　from　strainburst,　is　proposed　by　introducing　the　energy-based　strain　strainburst　criterion.　Thirdly,　the　proposed　model　is　verified　by　simulation　of　tunnel　excavation　process　and　mine-by　experimental　tunnels.　Finally,　the　comprehensive　analysis　of　influence　of　loading　and　unloading　on　the　strainburst　mechanisms　are　conducted.　The　results　demonstrate　that　the　variation　of　energy　over　time　for　loading　and　unloading　cases　are　significantly　different　and　the　trend　in　the　intensity　of　strainbursts　around　the　chamber　can　be　referenced　from　the　results　of　the　laboratory　model　test.　©　2025