Abstract:In order to obtain similar materials for tunnel model tests with wide matching and simple preparation methods, engineering materials such as gypsum, cement, river sand, and machine-made sand were selected, so as to meet the requirements of pre-grouting model tests for tunnel fault fracture zone that investigate the grouting effect of permeable crystalline slurry. Similar materials for surrounding rock, fracture zone, and tunnel lining were prepared through methods such as similarity constant calculation, material selection, and performance testing. The results show that the similarity constant was determined, such as Cl=50, Cγ=1, CE=50, and CQ=2 500. The experiment is conducted based on an optimized material ratio and preparation process. Similar materials with weight, compressive strength, and elastic modulus ranging from 16.65 to 17.58 kN/m3, 0.21 to 0.93 MPa, and 29.72 to 113.74 MPa are prepared by using cement, river sand, and gypsum. When mRS∶mG∶mC∶mW=1∶0.15∶0.03∶0.04, the prepared materials meet the test requirements. Selecting machine-made sand with an average particle size of approximately 0.4 mm as a similar material for the fracture zone can effectively avoid particle size effects and reasonably simulate the characteristics of loose and broken rock and soil. Similar materials with an elastic modulus of 0.38?0.62 GPa are prepared by using gypsum, barite powder, and cement. When mG∶mBP∶mC∶mW=1∶0.09∶0.05∶1.4, the prepared materials meet the test requirements, and the self-made polyvinyl chloride (PVC) assembly mould is used for pouring. The results indicate that similar materials of surrounding rock, faults, and lining all meet the similarity relationship requirements of tunnel fault pre-grouting model tests. At the same time, by adjusting the ratio, the research results can provide more material choices for similar engineering simulations.