## 6 Results and Discussion
### Monitoring of PW-1 Roadway  
Monitoring of PW-1 was conducted at six measurement stations--namely two stations per roadway support test section. Based on the analysis of the results, it can be observed that on the first test section (gauges installed at chainage 225 and 280 m) after the roadway divrage, the steel arch support at 225 m had significantly more load than at 280 m (Figure 16). The maximum load at 225 m was 45 kN, while only 16 kN at 280 m. During longwall exploitation, the highest recorded force was approximately 72 kN, also at 280 m. A detailed interpretation of the results reveals the arch sliding phenomenon despite the relatively low load values. It suggests highly asymmetrical loads, especially on the sidewall arches, which were not monitored. Also, asymmetrical yielding can be interpreted from load cell values obtained at test section III (538 m and 605 m), where the maximum load reached as high as 71 kN, while only reaching 30 kN at the same time in the other cell. In the second test section the loads were the least, being no higher than 19 kN. Notably, the load values recorded on the wooden ribs were significantly higher than those on the steel arch support (Figure 17). Only the rib located at 360 m recorded a load almost to the same extent as the steel arch support counterpart. In comparison, the loads on the wooden rib at 410 m (test section II) greatly exceeded the arch support loads (max. 170 kN) and approached its load-bearing capacity limit. In the second test section, bolting a larger roof area led to the redistribution of stresses on the sidewalls, including the wooden rib installed behind the longwall face, and simultaneously reduced the load on the support frames. Measurements using measurement bolts illustrate the substantial loads carried by the bolt support (Figure 18), which were definitely higher at tested stations II and III. The maximum total load was reached at chainage 610 m--320 kN, and at chainage 362 m--272 kN and chainages 412 m and 542 m--230 \(\div\) 240 kN. This proves that the load of the damage zone in the roof was mainly carried by strand bolts. Displacement measurements of the roof, initiated a few months after the roadway excavation, showed small values ranging from 6.6 cm ahead to 10.2 cm behind the longwall face, but only in the tested Section I (Figure 19), where strand bolts on resin cartridges were installed. The separation of roof rocks in tested sections II and III, where cable bolts where injected, was considerably smaller. Using Bullflex bags on the roof arches in Section II caused roof bed movements in both directions and a further decrease in the roof rock separation. Figure 16: Measurement results obtained from the load cells installed on the roof arch of support frames in PW-1 roadway. Figure 19: Total displacement of roof rock beds in PW-1 roadway. Figure 17: Measurement results obtained from the load cells installed on wooden cribs in PW-1 roadway. Due to technical reasons, stress change measurement, both ahead and behind the longwall face, was feasible only at one measurement base located in the second test section (Figure 20). The roof reinforcement, with the help of bolts and their stiffening, resulted in increasing horizontal pressures toward the developing goat. The stress direction ahead of the longwall face was changing constantly, causing variations in the loading directions on the support (Figure 21). This was one of the reasons why the steel arch support experienced less load due to a reduction in vertical pressure. Additionally, stress changes ahead of the longwall face practically doubled the value of primary stresses. At a depth of approximately 900 m (\(\sigma_{z}\) = 22.5 MPa), the increase was around 20 MPa. Therefore, if the rock mass is not heavily cracked and relieved, and there is no significant rotation of stress direction, such a situation is possible. However, it is crucial to note that at a triaxial stress state, the higher stress is primarily carried by the rock mass itself.