The occurrence environment and failure characteristics of explosive rockburst were collected and analyzed to explore the formation and evolution process of explosive rockburst in high geo-stress tunnels.The matrix discrete element numerical software MatDEM was used to simulate the phenomenon of explosive rockburst,and the mechanism of explosive rockburst was discussed.The results show that:(1)Explosive rock burst is a new type of rock burst phenomenon,rich in meso-fractures and squeezes rigid rock tunnels in high ground stress area of the suture zone.Under the action of excavation unloading disturbance,the surrounding rock bursts and breaks,and the sudden high-speed jet is accompanied by a large amount of dust.(2)The formation and evolution process of rockburst is divided into four stages:fracture activation and development stage,fracture aggregation and broken rock stage,high-speed jetting stage of broken rock block,and free-falling stage of broken rock block.(3)It is revealed that the geomechanical model of rockburst is tension-shear-jet type:under the action of excavation unloading disturbance,the surrounding rock of extruded rigid rock tunnel,which is rich in micro-fractures occurs aggregation fracture with tension failure as the primary and shear failure as the auxiliary.The elastic strain energy accumulated by the original extrusion suddenly releases and gives the broken rock high kinetic energy,and then the high-speed jet occurs.The research results provide a new understanding of rockburst formation and evolution process in complex rock tunnels in high-stress areas of the suture zone.
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