Physical model test of tunnel complex surrounding rock progressive failure based on strength-reduction similar materials

Similar materials are key to geomechanical model tests of tunnels. The strength-reduction method is commonly used in geotechnical engineering. In this study, a similar material for quantitative strength-reduction by temperature change was developed to simulate the strength-reduction method. Similar materials include paraffin wax, quartz sand, and barite powder. The parameters of similar materials at different temperatures were tested. The strength parameters of similar materials were quantitatively controlled through temperature changes to reduce their strength. Physical model tests were conducted for the progressive failure of a tunnel based on similar materials with a temperature control system. Physical model tests were carried out with the Hongyan Village tunnel complex as the engineering background; the research results revealed the deformation, force, and damage characteristics of the tunnel complex surrounding rock. The results were compared with calculated results using an FEM-based strength- reduction method. Physical model tests can simulate the process and characteristics of progressive failure of the tunnel surrounding rock and provide a reference for assessment of the factor of safety (FoS) and ultimate bearing capacity.