Evaluation method of grotto rock mass deterioration based on infrared thermography

The deterioration evaluation of grotto rock mass is an important foundation for its protection and reinforcement. In this study, the thermal effusivity and crack parameters of rock mass were obtained using infrared thermography (IRT), and a set of index system for the deterioration evaluation of rock mass was established. Based on the comprehensive weighting method and improved technique for order preference by similarity to ideal solution (TOPSIS), the evaluation method of grotto rock mass deterioration based on infrared thermography (EGD-IRT) was constructed. This method quantifies and classifies the deterioration level of rock mass using the deterioration index, which was validated and applied. The results indicate that the deterioration index of grotto rock mass can comprehensively reflect the damage to the internal structure and loss of external material of rock mass, and it is consistent with the comprehensive evaluation result of P-wave velocity and mass. Powdering, hollowing and cracks are the main reasons for the spatial heterogeneity distribution of the deterioration index of grotto rock mass. Among them, the cracks generally control the deterioration zoning of rock mass, with a negative correlation existing between the bulk density of cracks and the average deterioration index in different regions. The EGD-IRT can comprehensively analyze the deterioration status of rock mass from both the overall and local levels, thus determining the deterioration grade and unstable parts of grotto rock mass. The results of this study provide valuable guidance for the conservation of grotto temples.