## 3 Weak Interlayer Identification Method
### Identification of a Weak Interlayer in Geological Borehole  
There are differences in texture characteristics, integrity characteristics and acoustic response characteristics of the weak interlayer in the geological borehole. The contour characteristics of the geological borehole have a certain impact on the interpretation of the results of optical imaging and acoustic scanning in the borehole. Therefore, based on the optical image and acoustic scanning data, considering the texture characteristics, integrity characteristics, acoustic response characteristics and contour characteristics of the borehole wall, this paper proposes a recognition method suitable for the weak interlayer. The position information of the weak interlayer in the borehole rock mass structure is highlighted by organically fusing the hole wall texture feature response function TF, the hole wall integrity feature response function TF, the hole wall acoustic feature response function AF, and the hole wall contour feature response function CF. The corresponding weak interlayer identification block diagram is shown in Figure 6.  
In this paper, before the identification of the weak interlayer in the geological borehole, based on the original hole wall image fi, the hole wall texture feature response function TF, the hole wall integrity feature response function IF, the hole wall acoustic feature response function AF, and the hole wall contour feature response function CF are fused to reconstruct the corresponding rock wall image. Construct the borehole wall reconstruction image FI considering various hole wall features, and the expression is:  
\[FI(i,j)=\lambda_{1}\cdot TF(i,j)+\lambda_{2}\cdot IF(i,j)+\lambda_{3}\cdot AF( i,j)+\lambda_{4}\cdot CF(i,j) \tag{13}\]  
Among them, \(\lambda_{1}\), \(\lambda_{2}\), \(\lambda_{3}\) and \(\lambda_{4}\) are the weighted values of different response functions, usually taken as the average value, and can also be adjusted appropriately according to the actual situation. At the same time, the four parameters also need to meet the basic requirements of \(\lambda_{1}+\lambda_{2}+\lambda_{3}+\lambda_{4}=1\). When the hole wall texture feature and the hole wall integrity feature are obvious, that is, the larger the value of the corresponding hole wall texture feature response function TF and the hole wall integrity feature response function if, the smaller the possibility of corresponding weak interlayer. When the hole wall texture feature and the hole wall integrity feature are not obvious, that is, the corresponding values of the hole wall texture feature response function TF and the hole wall integrity feature response function TF are small, the greater the possibility of a corresponding weak interlayer. When the acoustic characteristics of the hole wall and the contour characteristics of the hole  
Figure 6: Identification block diagram of weak interlayer. wall are obvious, that is, the larger the value of the corresponding acoustic characteristic response function AF of the hole wall and the contour characteristic response function CF of the hole wall, the greater the possibility of corresponding weak interlayer. When the acoustic characteristics of the hole wall and the contour characteristics of the hole wall are not obvious, that is, the values of the corresponding acoustic characteristic response function AF of the hole wall and the contour characteristic response function CF of the hole wall are small, the possibility of corresponding weak interlayer is smaller. Through the grayscale processing of 256 values for the four-hole wall feature values, the smaller the FI value of the borehole wall reconstruction image formed, the greater the possibility of corresponding weak interlayer, that is, the darker the borehole wall reconstruction image FI, the higher the probability of corresponding weak interlayer. Combined with the subsequent image processing, the weak interlayer can be recognized.