Abstract: The excavation unloading activities in deep hard rock tunnels often induce high-intensity rockburst disasters, which has become a key issue affecting the safety construction of tunnels. The physical model test is an important method to study the deep tunnel excavation, and the properties of model materials have great influences on the testing results. Thus, it is the key to prepare materials suitable for the physical model test. Based on the development of the traditional rockburst model materials, this paper introduces the rockburst proneness index and brittleness evaluation index. Combing with the orthogonal design method and sensitivity analysis, the experiments were carried out to investigate the rockburst model materials with low-strength and high-brittleness. We analyzed five influencing factors, including the quartz sand content, barite content, water content and the mass ratio of high-strength gypsum and cement. Each factor was set at five levels, a total of 25 matching schemes. The material strength, mechanical parameters, rockburst proneness index and brittleness evaluation index of model materials were measured in each matching scheme, and the variation of these parameters and indexes were studied under different design levels. Finally, the relationships among the influencing factors, rockburst proneness and brittleness of the selected rockburst model materials were discussed. The results show that: 1) According to the rockburst proneness index and brittleness evaluation index, the prepared model materials meet the requirements of the physical model tests. 2) It is important to control the contents of barite powder and water and to adjust the mass ratio of high-strength gypsum to cement properly.

Key words: brittle rock, rockburst, model material, brittleness index