Ratio Test and Characteristic Analysis of Similar Materials in White Sand Rock

Rock burst has become a common disaster in tunnel engineering. Physical model test is an effective scientific means to simulate and solve the problem of rock burst. Material selection and ratio are the key to make physical model. The white sandstone of Yuezhishan tunnel in Emi section of Chengzhou-Kunming Railway was selected as the simulation object to prepare the similar material of white sandstone, and the elastic energy index, brittleness index and residual elastic energy index were introduced. The orthogonal design method was used to mix the similar material and the sensitivity analysis method of influencing factors was used to analyze the test results. With quartz sand, iron powder, gypsum, cement, retarder and water reducer as the main materials, four influencing factors of quartz sand content, iron powder content, gypsum cement ratio and sand particle size were selected, and four design levels were set for each factor. There were a total of 16 matching ratio schemes. The uniaxial compressive strength, tensile strength, modulus of elasticity, elastic energy index, brittleness index and residual elastic energy index of the materials in each test scheme were measured, and the variation rules of these indexes with the four influencing factors were compared and analyzed. Finally, a reasonable material ratio scheme is selected to obtain similar white sandstone materials meeting the requirements. The test results show that: the material prepared based on elastic energy index, brittleness index and residual elastic energy index can meet the requirements of model test for similar materials of white sandstone; using cement as a cementing material can slow the post-peak curve of similar materials and effectively increase the energy storage capacity of materials; to produce similar materials of white sandstone with medium-strength rockburst tendency, it is necessary to reasonably control the content of quartz sand and the ratio of gypsum and cement, and then adjust the content of iron powder and the particle size of quartz sand according to the actual situation.