## 2 A Brief Introduction of the Model Test  
The detailed model test process is referred to in another two papers [39; 40], and is only briefly described in this paper, as follows:  
1. For the instrument providing the biaxial static loads in the model test, the corresponding size of the specimen was 1.6 m (length) \(\times\) 1.3 m (height) \(\times\) 0.4 m (thickness), as shown in Figure 1. 2 The prototype of the model test was the deep-buried underground engineering surrounding rock, and the physical and mechanical parameters of the prototype are shown in Table 1. The corresponding intact rock simulation material was low strength cement mortar containing cement, sand, water, and a plasticizer. Meanwhile, the stress similarity coefficient \(C_{\sigma}\) between the prototype and simulation material was 20. Through a series of tests, the mechanical parameters of the cement mortar material were obtained and are shown in Table 1. In addition, the joints in the model test samples were simulated by the mica plates, and their normal and tangential stiffnesses were 12 GPa/m and 7.53 GPa/m, respectively, and were obtained through laboratory tests. 3 According to the number and the angle of the joints, a total of three model test samples were made, named T1, T2, and T3 respectively, as shown in Figure 2. Due to the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Type** & \(R_{c}\)/**MPa** & \(\sigma_{V}\)/**MPa** & \(E\)/GPa & \(\varphi\)/(\({}^{\circ}\)) & \(C\)/MPa** & \(\mu\) & \(\rho\)/**kg/m\({}^{3}\)** \\ \hline Prototype & 120 & 12 & 50 & 30 & 30 & 0.223 & 2600 \\ Similar & 5.864 & 0.613 & 5.226 & 23.2 & 1.49 & 0.203 & 1980 \\ material & & & & & & & \\ \hline \hline \end{tabular} Where, \(R_{c}\), \(\sigma_{V}\), \(E\), \(\sigma_{V}\), \(\mu\) and \(\rho\) are the uniaxial compressive strength, tensile strength, elastic modulus, internal friction angle, cohesion, poisson ratio, and density of the prototype and similar material, respectively.  
\end{table} 
Table 1: Physical and mechanical parameters of similar materials and the prototype of the intact rock. Figure 1: Multifunctional testing machine for the rock and soil: (**a**) test equipment; (**b**) static loading schematic. structural characteristics of the cylindrical charge, two test sections were uniformly arranged along the thickness direction in each model test sample. Four measuring lines were arranged on each section to measure the stress and strain at different distances from the explosion source. Sixteen strain measuring points were arranged on the strain testing section, ranging from 1 to 16, and eight stress measuring points were arranged on the stress testing section, ranging from 17 to 24. 4. The T1 and T2 samples were designed to study the propagation of the blasting stress waves in intact rock, and the normal or oblique impact of the blasting stress wave on the rock mass containing joints with a different number and angle, and the corresponding research objects of the T1 and T2 test samples were intact rock and single-joint and double-joints rock masses of 30\({}^{\circ}\), 60\({}^{\circ}\), and 90\({}^{\circ}\), respectively. Meanwhile, the T3 sample was designed to study the propagation of the blasting stress waves in intact rock and the normal jointed rock mass. According to the number of joints in the four measuring lines, the corresponding research objects were intact rock, 90\({}^{\circ}\) single-joint rock mass, 90\({}^{\circ}\) double-joints rock mass, and 90\({}^{\circ}\) three-joints rock mass. Figure 2: Layout of the measuring points and the joints of the model test samples (unit: mm): (**a**) T1 sample; (**b**) T2 sample; (**c**) T3 sample. (5) In the model test, detonating cords with a total length of 1.6 m and TNT (Trinitro-toluene) with an equivalence of 17.6 g were used as the explosive sources to generate the blasting stress wave, and the detonating cords were fixed in the seamless steel pipe in the center of the test samples through the wooden centering stent.