## 1 Introduction  
The economic growth of any nation is underpinned by the availability of metal mineral resources, which play a pivotal role in sectors such as construction, manufacturing, transportation, aerospace, and electricity [1, 2]. Projections indicate that the global demand for key mineral resources like iron, copper, and aluminum will continue to surge in the next 10-15 years, specifically from 2030 to 2035 [3]. Despite China ranking third in the world in terms of total mineral resources, accounting for approximately 12% of the global share, the per capita possession of these resources stands at only 58% of the global average, placing the country at 53 rd globally. Notably, the lower grades of crucial minerals like copper and iron ore have increased China's reliance on these resources [4], making the secure supply of mineral resources a direct determinant of the country's economic progress. The block caving method, renowned in the industry as the \"Underground Rock Factory\" [1], offers economic benefits comparable to open-pit mining [5, 6]. For deposits with low grades and large reserves, block caving is the preferred method of extraction [7]. Under suitable conditions, this approach can significantly reduce mining costs and activate mineral resources that are uneconomical and untapped due to their low grades [8, 9, 10]. This holds significant importance for reducing dependence on foreign mineral resources and ensuring the reliability of resource supply [11, 12]. Rock masses refer to geological bodiescomposed of blocks of different lithologies and structural planes of various scales and types. Due to the constraints of metallogenic conditions, the distribution of the natural metal ore body is often irregular, enriched with a large number of primary structural planes such as joints, fissures, and faults during tectonic evolution. Under the disturbance of blasting bottom pulling [13], on one hand, existing structural planes within the ore body extend and connect, forming macroscopic fracture planes. On the other hand, due to stress redistribution, the internal stress of the ore-bearing rocks near the free face exceeds its own strength, further crushing the ore body. The crushed ores will further squeeze, slide, and rotate each other, and the unsupported and collapsed ore body collapses under its own weight. This complex mechanical behavior of the ore body during undercut caving mining is difficult to describe through theoretical analysis [14]. Scholars, both domestically and internationally, have investigated the theoretical methods concerning the stability and ground pressure manifestation of the bottom structure in natural collapse methods and the stress evolution of the overlying rock layer. [PERSON] et al. [15; 16; 17] examined the influence of the bottom pulling method, tectonic stress, bottom structure height, and other factors on the bottom structure in natural collapse methods, proposing control measures. [PERSON] [18] analyzed the characteristics of stress changes in the bottom structure during natural chipping mining by monitoring stress during bottom pulling and chipping in the Copper Mine Valley mine. When studying and analyzing it, it is necessary to start from existing natural geological conditions, gradually progressing from macroscopic analysis to microscopic research, considering the impact of engineering activities. Various research methods are used to accurately predict the deformation of engineering rock masses and evaluate their stability [19; 20]. Currently, research into engineering problems related to rock bodies primarily relies on numerical simulation and physical experimentation alongside other methodologies. Among these, numerical simulation offers an intuitive simulation of crack expansion and rock damage processes. It effectively models the mechanical responses of rock bodies to environmental changes and engineering activities, being particularly suited to scrutinizing rock mechanics from a microstructural perspective [21].