## 3 Engineering Background  
The Jangfeng Iron Mine is located in the southwestern border of Yunnan Province, under the jurisdiction of Menglong Town, Jinghong City, in the Xishuangbanna Dai Autonomous Prefecture. The mine is situated 195\({}^{\circ}\) from Jinghong City, with a linear distance of 59 km and a road distance of approximately 75 km. It lies 9 km southwest at 211\({}^{\circ}\) from Menglong Town. The central geographical coordinates of the mine are 100\({}^{\circ}\)38\({}^{\circ}\)38\({}^{\prime\prime}\) E and 21\({}^{\circ}\)30\({}^{\prime}\)06\({}^{\prime\prime}\) N. The mine area extends in a northeast-southwest direction, stretching from Manfei in the northeast to 1.5 km northeast of Guofang in the southwest. The total length of the mine is 3 km, with a width of 0.6 km, covering an area of 2.0314 km\({}^{2}\), and it is conveniently accessible.  
The Jangfeng Iron Mine is divided into three phases: Phase I includes areas above the 340 m elevation, Phase II includes areas between the 100 m and 340 m elevations, and Phase III includes areas below the 100 m elevation. Phase II is further subdivided into the 100 m and 220 m levels. The mine is segmented into three ore sections, containing a total of 13 ore bodies. In sections I, II, and III, the ore bodies dip at angles ranging from 105\({}^{\circ}\) to 160\({}^{\circ}\), with local reverse dips. The dip angles range from 75\({}^{\circ}\) to 89\({}^{\circ}\), with an average dip angle of 83\({}^{\circ}\). The longest strike length of a single ore body is 1914 m, while the shortest is 44 m. The maximum dip extension reaches 968 m, with a minimum of 18 m. The ore-bearing elevations range from 739 m to 390 m, with a total vertical height of 1129 m. The ore bodies have an average thickness of 1.75 to 28.76 m and consist of uniformly composed steeply dipping thin-to-thick ore bodies. Geological data for the Jangfeng Iron Mine are shown in Figure 8. The basis for the hierarchical selection in this paper comes from the mine production design data, as the mine is currently planning to mine the 100 m and 220 m levels. The topographic map and mining phase diagram of the Jiangfeng Iron Mine are shown in Figure 9.  
Due to the need for increased production capacity, joint mining of the 100 m and 220 m levels can effectively meet production expansion requirements. However, its safety must be specifically studied. Simultaneous mining of these two levels will inevitably intensify the disturbance to the surrounding rock, potentially affecting its stability. Although the surrounding rock of the Jangfeng Iron Mine consists of relatively hard rock formations, the presence of complex faults has resulted in highly fractured rock masses. Additionally, the development of alteration zones, weathered contact zones, and numerous joints and fractures further weakens the stability of the surrounding rock. This makes the tunnels prone to geological engineering issues, such as roof falls [34], sidewall spalling [35], and floor heaving [36], which can negatively impact the stability of the ore bodies. The mining area has developed more than 14 longitudinal and transverse faults, interwoven with each other. Among them, longitudinal faults dominate, with the largest ones being the F4 and F10 faults. The main ore bodies of the mining area are hosted between these two faults. Both faults extend discontinuously for over 3000 m and are roughly parallel to the fold axis. On the surface, the two faults are spaced 55-160 m apart, and their structural planes are classified as Grade II structural planes. The other faults are smaller in scale, generally extending 300-500 m, and are considered secondary fractures within the mining