## 4 Experimental Validation and Project Examples  
In this experiment, concrete material was used to simulate the rock mass, and 3D scanning and 3D printing techniques were used to obtain a structural plane of resin material highly similar to the real one [25]. The 3 DSL-600 printer was used for 3D printing, with a molding accuracy of \(\pm\)0.1 mm, which can meet the accuracy requirements of the simulated structural plane. When the concrete samples were poured, the artificial structural plane was arranged from different directions to obtain the simulated structural plane with different yields. The size of the concrete sample is: L \(\times\) W \(\times\) H = 300 mm \(\times\) 300 mm \(\times\) 300 mm. Considering the complexity of the rock structure, we generalized the rock's geometrical dimension in this experiment according to the need of the test. In most cases, the actual structural plane is not strictly flat, but has a certain undulation angle, roughness, and randomness in extension. The experiments were carried out by 3D scanning the surface model of the original structural plane of marble collected from the field, and 3D printing was used to obtain the structural plane of the resin material with different thicknesses close to the original structural plane, respectively. The process of making the simulated structural plane is shown in Figure 6. In order to compare with the simulated real structural plane, the resin material was used to make a flat structural plane of the same size. The size of the simulated structural plane was designed to penetrate the concrete sample. This way, the structural plane's occurrence can be measured conveniently after the sample is formed. In order to make the sample still have some strength after the structural plane is arranged, small holes of 20 mm in diameter are arranged around the simulated structural plane, and the small holes will not affect the structural plane cutting drilling. In consideration of  
Figure 5: Some common structural plane characteristics. (**a**) Rock veins filling. (**b**) Opening crack. (**c**) Texture features. the experimental purpose, metamorphic quartz sand was used as the prototype material. Quartz sand, cement, and water were selected as rock-like materials, and relevant information [26; 27; 28; 29] was consulted. After several proportioning tests, following the principle of easy experimental observation, the ratio of water:cement:altered quartz sand was determined to be 1:2:4. The mold shall be removed 48 h after the sample is poured and formed. The test shall be conducted after curing for three days under standard curing conditions. The distribution of structural planes within the rock mass is spatially complex and irregular, so two groups of structural planes with different production shapes were designed for this experiment. The two groups of structural planes were run through the concrete sample for experimental observation and contrast. Six boreholes were arranged at different locations, and the arrangement of each borehole and the structural plane is shown in Figure 7. A small water-grinding drilling rig with a 40 mm outer diameter drill pipe was used to drill into the concrete samples to obtain boreholes of 40 mm diameter, and a 32 mm diameter probe was used for the borehole camera. In these boreholes, ZK1, ZK2 and ZK3 were vertical boreholes, and ZK4, ZK5, and ZK6 were inclined boreholes with different inclination directions. Two sets of experiments were conducted with the flat structural plane and simulated structural plane. The structural plane parameters were the same in each set of experiments, and the borehole arrangement was the same. The structural plane and borehole arrangement are shown in Figure 7 below. In the sample preparation process, due to the insecure fixation of the embedded structural plane and the deformation of the concrete during the forming process, the  
Figure 6: The fabrication of simulated structural plane. (**a**) Three-dimensional model of structural plane; and (**b**) 3D printing of simulated structural planes.