## 5 Conclusions  
In this paper, based on the combined measurement technology of borehole image and sound, a method of identifying weak interlayer is proposed, which combines the borehole optical image information and the rock wall acoustic response data. The two technologies adopted in this paper can complement and confirm each other's advantages (of optical image and acoustic scanning technology), compensate for the shortage of a single data source in the process of changing information extraction, and combine the complementary characteristics of different data analysis methods to improve the accuracy and objectivity of rock mass structure data interpretation and interpretation, which can provide a scientific basis for landslide control. Combined with the case analysis, the main conclusions are as follows: (1) by adopting the borehole survey mode, combining optical imaging and acoustic scanning, the optical image information of the borehole wall and the 360-degree acoustic full pulse reflection information of the borehole circumference can be effectively captured, and more comprehensive multi-source data can be provided for the identification of weak interlayer. (2) The identification result of the weak structural plane of this method is more accurate than that of the traditional optical borehole imaging technology. It can solve the problem that the traditional optical imaging method does not consider the difference characteristics of the internal structure of the borehole rock mass, thereby effectively distinguishing the types of structural planes and dividing the areas where the weak structural plane is located. (3) The identification results of the weak structural plane in this method are more abundant than those of the traditional wave velocity testing technology, which can improve the shortcoming that the traditional wave velocity testing method can only roughly judge the sound velocity changes of rocks at different formation depths, solve the comprehensive reflection characteristics without directionality, and effectively identify and characterize the potential weak structural areas.  
(4) The photo-acoustic combined measurement technology brings applied innovation to the exploration of the weak interlayer of the landslide. On the one hand, it enriches and develops the existing weak layer detection technology of the landslide geological body; on the other hand, it provides a feasible way for the classification of the structural plane types in the borehole, which can improve the accurate identification ability of the weak interlayer in the landslide geological body.  
Conceptualization, J.W.; Formal analysis, J.W.; Funding acquisition, J.W.; Investigation, J.H.; Resources, H.M., F.W., Y.W. and Z.H.; Writing--review & editing, [PERSON] All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation for the Youth of China (41902294); the Natural Resources Research Project of Hubei Province (ZRZY2022 KJ08).  
Not applicable.  
All data, models, and code generated or used during the study appear in the submitted article.  
The authors declare no conflict of interest.