## 3 Analysis of Resonance Test Results  
Figure 5 shows the test results of the vibration acceleration for specimens containing 60% and 90% rock proportions, respectively.  
As shown in Figure 5, the vibration damping rate of bimrocks with a rock proportion of 90% was greater than that of bimrocks with a rock content of 60%. Due to the notable rise in the void structure of bimrocks with a 90% block proportion, it is estimated that the well-developed void structure accelerates the energy dissipation and results in the increase in the vibration damping rate. However, the differences were relatively insignificant and easily affected by the quality of signal acquisition. In contrast, the acceleration resonance frequencies of the specimens with different RBPs showed distinctive differences. Additionally, stable test results were still obtained when the test signal was poor, which could better distinguish the physical and mechanical properties of welded bimrocks. On the basis of the operator's manual of the resonance frequency tester [29], the acceleration resonance frequency can be converted into a dynamic elastic modulus as follows:  
\[E_{dy}=\lambda\times\frac{l\times M}{d^{2}}\omega_{a}^{2}, \tag{1}\]  
where \(E_{dy}\) is the dynamic modulus of elasticity, \(\omega_{a}\) is the acceleration resonance frequency, \(l\) is the length of the specimen, \(d\) is the diameter of the specimen, \(M\) is the mass of the specimen, and \(\lambda\) is the system constant, which is calibrated to 5.093 for a cylinder specimen and 4.000 for a prism specimen [29].  
The relation between \(E_{dy}\) and \(RBP\) is presented in Figure 6. A clear decreasing trend in the dynamic elastic modulus was observed with an increase in the RBP value. An exponential relation was obtained through the method of least square, as shown in Equation (2). According to the test data in Figure 6, the dynamic elastic modulus of each group had limited dispersion due to the strict specimen preparation process, which contributed to the high \(R^{2}\) in the fit Equation (2). The fit results also indicate that the exponential type function can effectively illustrate the quantitative relation between the dynamic elastic modulus and the RBP. Additionally, the dynamic elastic modulus can be used as an effective index for judging the mechanical properties of welded bimrocks.  
\[E_{dy}=-1.3\cdot 10^{-5}\cdot\exp(-RBP/0.063)+32.01,\ R^{2}=0.97, \tag{2}\]  
Figure 5: Time frequency analysis of the vibration signal.  
Figure 8 shows the relation between the UCS and the RBP of bimrocks. The UCS of bimrocks descended gradually with the increase in RBP. The fit result for the curve in Figure 8 is presented in Equation (3) using the least-squares method. As can be seen, a strong exponential correlation was found between UCS and RBP.  
\[UCS=237.91\exp(-RBP/0.37)-17.66;\ R^{2}=0.94, \tag{3}\]  
Figure 9 shows the failure morphology of specimens with different rock contents. Vertical cracks through the matrix represent the dominant failure pattern for the specimens with RBPs lower than 70%. The matrix strength was shown to have a strong influence on the UCS of the welded bimrocks within this range of RBPs. The other kind of crack appeared with a further increase in the RBP, which occurred along the interface between the soil and the rocks. The failure pattern was a combination of both splitting and sliding. Thus, the interface strength also affected the UCS of the welded bimrocks. When the rock proportion reached 90%, the UCS of the welded bimrocks was mainly dependent on the interface strength between the soil and rock. The split failure was hard to find under such conditions. In contrast, localized shear failure was observed due to the well-developed void structure.