Deformation and failure behavior of fractured rock roadway: physical simulation with 3D printing

Complex structure and fracture development in surrounding rock of coal mine greatly affect the roadway stability. It is of great theoretical and engineering siginificance to study the deformation and failure characteristics of roadway in fractured surrounding rock. Based on the engineering background of 12 upper 302 auxiliary haulage roadway in a coal mine, western China, well-integrated and fractured surrounding rock roadway physcial models were prepared with sand 3D printing technology. Through the combination of biaxial loading tests and digital speckle technology (DIC), the influence of surrounding rock fractures on the deformation and failure law of roadway and the failure zoning characteristics of fractured surrounding rock were explored. The results show that the layered printing of different coal rock strength can be realized by using silica sand with particle size of 0.070~0.140 mm and 0.100~0.200 mm and changing different matrix ratios, which meets the strength ratio relationship of each coal rock. For the well-integrated surrounding rock roadway model, cracks first appear at the shoulder angle of the roadway, and then the two sides breaks and the roof sinks, mainly shear failure. In comparison, the failure of fractured surrounding rock roadway mainly evolves along the prefabricated cracks, and the damage of the two sides is more obvious with broken blocks. This reproduces the deformation and failure characteristics of the actual engineering roadway to a certain extent. Through the field measurement of fracture parameters, the fracture parameters can be implemented into the physical model of the roadway through the sand-mold 3D printing technology.