A Modelling Resin Material And Its Application In Rock-Failure Study: Samples With Two 3d Internal Fracture Surfaces

The mechanism of fracture propagation, interaction and coalescence inside rock masses is a highly concerned issue in geotechnical engineering. But as it is difficult to manufacture 3D internal pre-fractures and observe directly the failure evolution process inside real rocks or their opaque similar materials, most previous studies have been limited to 2D conditions. The experiment investigation on 3D rock failure is still in a preliminary stage. In this study, a resin material has been developed by extensive formula tries. It is absolutely transparent and the ratio of tension-compression strength (brittleness value) can be 1/6.6 at -10 to -15 degrees C. It is much more brittle and rock-like than analogous materials used by former scholars. A set of preparation, casting mould, and post-processing technologies were established and specimen-making with multiple pre-fractures is enabled. In the designed scheme, specimens are made with two parallel internal fracture surfaces yet of four different stagger separations. Uniaxial tests were carried out and the stress-strain relationship is analysed. It is shown that the specimen has gone through four stages as the traditional rock test before failure. Many diverse forms of secondary fractures, such as wrapping wing crack, petaloid crack, and giant quasi-wrapping fracture surface, which were not found in 2D conditions have appeared and their evolutions were clearly seen in each stage.