Abstract: It is known that two-body rock structure, formed by one hard rock and another soft one, is the most basic rock structures of rockburst and coal & gas outburst. It investigated entirely the deformation and failure behavior of two-body rock structure by model of strain hardening & softening (SS) from FLAC3D, which varied with mechanical properties and geometry parameters of the structure. Firstly, the elastic rebound and strain localization was reappeared first time by es_plastic contour from FLAC3D. It also indicated by the simulation that the strength difference is one of the necessary conditions of the burst failure while the modulus increase of hard part decreases the burst energy. Secondly, it distinguished failure pattern of one-body-two-property & two-body-two-property with modeling, which suggests that the strength increase of interface can decreases the burst energy. Finally, it implicated that the burst failure happened only if the ratio of height and radius of rock stay in a proper alteration (for soft part is 0.5, hard part is 0.05). With simulation of same height of soft part, the burst time of failure deduced with the height ratio of the hard and soft, which indicated a more sudden burst failure.

Key words: two-body rock structure, numerical simulation, elastic rebound, strain localization, rockburst