## 2 Project Overview  
Zhongjiu Iron Mine is a subsidiary of the Ma Steel Group Gushan Mining Limited Liability Company (Maanshan, China). It is situated 7.5 km south of Dangtu County, Anhui Province. The administrative division falls under the jurisdiction of Zhongshan Village, Nianpian Town, and Dangtu County. The mine region has a well-established surface water system consisting primarily of ditches and ponds. The saturated area covers around 15% of the total area. The Qingshan River flows past Dangtu and the Yangtze River, about 1.3 km east of the mine. The Qingshan River flows from south to north in the eastern part of the mine. The riverbed has a minimum elevation of \(-\)2 m and a maximum flow rate of 568 m\({}^{3}\)/s. The greatest recorded flood level is 12.36 m. The stratigraphy of the Zhongjiu Iron Ore Mine exhibits a high level of complexity, characterized by variations in lithology and the presence of numerous faults and fissures. The primary aquifer in the mine consists of robust water-rich rock formations, namely the fourth series gravel and pebble layer, as well as the sand and shale fissure layer located beneath the ore body of the Huangmaqing Group. The water recharge mechanisms in the ore deposit are complex, with the main factors being the infiltration of pore water and water flowing through fractures, while karst fissures contribute as secondary factors. The upper and lower layers of the deposit are primarily composed of the Gushan Group and the Zhouchong Village Group. The surrounding rocks in the mining area consist mainly of class IV bedrock, which has low structural integrity. The rock hardness coefficient ranges from 2 to 9, indicating that it belongs to a soft and weak rock formation. The rock hardness coefficient ranges from 2 to 9, classifying it as a weak type of rock. The lithology of the stratum between the depths of 308 m and 438 m is a little worn sodium long diorite. The mining region contains one primary ore body and fifty-three smaller ore bodies. The primary ore body is situated in the contact zone between the Zhouchongcun Group's tuff and the Gushan Group's varied volcanic clastic sedimentary rocks. According to the roadway development plan, the Zhongjiu Iron Mine air shaft \(-\)380 m level 2# alley in the roadway development process will pass through the mine rock contact zone. The geological conditions of the 2# vein-piercing lane of Zhongjiu Iron Mine are shown in Figure 1. In the previous roadway excavation, Zhongjiu Iron Mine adopted the \"steel bracket + anchor\" joint support form of support, but the two sides of the roadway inward-contraction, cracking, bottom drum and steel frame deformation, and other safety issues in the palm face of the drenching, rock collapse, and other issues. The ore body exposed during the tunneling of #2 through the vein is black, has a powdery mud structure, is easy to muddy in contact with water, and has serious rock fragmentation. In view of the roadway excavation through the contact zone of the ore and rock, the Zhongjiu Iron Mine decided to adopt the technique of over-curtain grouting and water-blocking to achieve the purpose of water control and control the stability of the surrounding rock. After on-site core drilling and sampling, according to the \"engineering rock test method standard GB/T50266-2013 [21]\" will be processed into 12 samples of size \(\Phi\)50 m \(\times\) 100 mm and six samples of size \(\Phi\)50 mm \(\times\) 25 mm standard specimen for the uniaxial compression  
Figure 1: Geological conditions of Zhongjiu Iron Mine’s 2# vein-piercing lane. (**a**) Geographical location map of Zhongjiu Iron Mine; (**b**) \(-\)380 m horizontal 2# threading lane location diagram; (**c**) Geological profile. test, full stress-strain infiltration test, and Brazilian cleavage test. The average of the test results for the enclosing rock physical-mechanical parameters will be used in subsequent numerical simulations.