## 2 General Situation of the Engineering and Analysis of In Situ Stress  
Ronghua No.1 Mine is located within the territory of Yonghe Town, Jidong County, Heilongjiang Province. The strike length measures 8.5 km, with an inclined width of 8.7 km, covering an area of 74.25 km\({}^{2}\), and has an output capacity of 2.1 million tons per year. Currently, the primary coal seam under exploitation is the 6A# coal seam, which has an approximate thickness of 3 to 4 m. The column diagram of the rock strata is presented in Figure 1.  
The 6A# left 2 nd roadway in the East First Mining Area of Ronghua No. 1 Mine is a coal roadway, buried at an approximate depth of 850 m. The vertical distance between the goat above the roadway roof and the coal seam is relatively large, exceeding the effective influence range of mine pressure manifestation. At the same time, the coal bodies on both sides of the roadway show good integrity, not affected by the goat, and are in the original stress state. The cross-sectional dimension of the roadway excavation is 4 m \(\times\) 3 m. The anchor bolts are reinforced steel anchor bolts of \(\Phi\)20 mm \(\times\) 2000 mm, with a pattern of 1200 mm \(\times\) 1000 mm; the anchor cables are steel strand anchor cables of \(\Phi\)21.8 mm \(\times\) 6200 mm, with a pattern of 1200 mm \(\times\) 1000 mm. The roadway support  
Figure 1: Stratigraphic column. employs a combined support scheme of anchor bolts--anchor cables--nets, as illustrated in Figure 2.  
After supporting the roadway for some time, the deformation of the surrounding rock is serious: the roadway roof has obvious sinking damage, the anchor bolts and nets appear close to failure, the two sides of the roadway have contracted, and there is section reduction, all of which seriously affects production. The roadway deformation is shown in Figure 3.  
The results of on-site statistical analysis reveal that the roadway roof deformation is marked, with substantial two-sided displacement observed. It has been preliminarily ascertained that the roadway is subject to high-stress conditions, characterized by a horizontal principal stress that exceeds the vertical principal stress, exhibiting typical features of a tectonic stress field. To clarify the distribution characteristics of the stress field around the roadway, it is planned to conduct in situ stress testing work. The in situ stress testing method adopted in this work is the hollow inclusion stress relief method. By means of the hollow inclusion stress gauge, this method can accurately obtain the magnitude of the in situ stress within the surrounding rock. The testing process is as follows: First, drill holes in the side of the roadway. The drilling angle should be controlled within 3-5\({}^{\circ}\), and the depth should reach 6-7 m to ensure that it is not affected by the surrounding rock stress field. Subsequently, place the hollow inclusion stress gauge into the hole and use glue to firmly bond the stress gauge to the hole wall, ensuring a stable mechanical connection between them. After the stress gauge is installed, let it stand for 24 h. After the glue is fully cured, carry out the over-coring stress relief drilling operation according to the pre-determined graded depths. The drilling depth of each grade is set to 3 cm. Immediately stop drilling after completing the over-coring stress  
Figure 3: Deformation of surrounding rock in the roadway. Figure 2: Support scheme diagram of 6A# Left 2 nd Roadway. relief of each grade, and read and record the data. Based on the fundamental principles for the layout of initial rock stress measurement points, and considering both underground production and construction activities as well as the mining area of Ronghua No. 1 Mine, three measurement points were selected for the actual measurement of initial rock stress within the exposed section of the existing roadway.