## 1 Introduction  
China has focused on the development and use of hydropower projects in the lower reaches of the Yalong River and upper reaches of the Jinsha River, with the aim of \"achieving carbon neutrality before 2060\". Southwest China is located in the high mountain valley area of the Hengduan Mountains on the eastern edge of the Qinghai-Tibet Plateau. It is characterized by its high altitude, high ground stress, and complex rock structure. For hydropower plants in this area, underground caverns are often the most practical and cost-effective option for meeting topographic, spatial, building layout, and construction requirements. The construction of underground caverns for hydropower projects will face great risks and challenges due to the strict requirements for rock quality, construction cycle and safety standards, and complicated construction procedures. The surrounding rock is likely to become unstable and damaged during construction due to poor excavation and delayed support, which could result in casualties and property losses. For example, the Baihetan underground powerhouse has the largest excavation size in the world. During the excavation of underground caverns, rock collapses dominated by high geostress and geological structures posed serious threats to field construction [1]. An unexpectedly powerful rock burst that occurred in November 2009 during the construction of the Jinping-II drainage tunnel destroyed all the support systems in the affected sections, seriously damaged the TBM equipment, and killed seven workers [2]. Tunnel excavation of the Neelum-Jhelum Hydropower Project in Pakistan has been hindered by the ground composition of the Himalayas, faces the project complexities, geological environments involving significant overburden and tectonic stresses, and effects of the excavation method on tunnel stability. This causes time and cost overruns directly [3]. Therefore, it is crucial to assess the stability of surrounding rock during the excavation and unloading of underground caverns, to promptly inform the constructor of unstable areas, and to implement a reasonable construction and support reinforcement plan. As an important research method, numerical modeling is now widely used by scholars to study the rock excavation and unloading process, and predict the instability failure mode and impacted area in the rock mass. To determine the deformation and stress distribution around the caverns and to analyze the impacts produced by weak structural planes and multiple caverns in the rock mass, [PERSON] et al. [4] developed a three-dimensional finite element model for analyzing the stability of underground caverns. [PERSON] et al. [5] examined the impact of faults on the plastic zone and displacement of underground caverns using the Universal Distinct Element Code (UDEC) numerical modeling software. [PERSON] et al. [6] performed displacement-based back analysis using finite element and discrete element methods to determine geomechanical properties of the rock in underground caverns, such as stress ratios and joint parameters. [PERSON] et al. [7] investigated the failure mechanisms and movement characteristics of rockfalls through a three-dimensional discontinuous deformation analysis (3D DDA) method. [PERSON] et al. [8] conducted pore-scale modeling on the methane hydrate dissociation and transportation in the reconstructed three-dimensional models of the MH-bearing sediment. [PERSON] et al. [9] studied the acoustic emission pattern during the excavation and unloading process of underground plants using the FLAC/PFC coupled numerical modeling method. [PERSON] [10] studied the stability of rock with anisotropic fractures in a tunnel using discontinuous deformation analysis (DDA) in the discrete element method (DEM). In addition to numerical simulation, Field monitoring is also a common method for studying the mechanical response and stability of the underground rock. Field monitoring data can visually reflect the stress-strain characteristics of the rock mass in underground caverns.