![]() This approach shows promise as an efficient measure for the ground control of longwall entries and prevention of coal bursts. More importantly, LHF can significantly release mining-induced stress and alleviate microseismic events resulting from the fracturing of thick, strong rock strata above the gob area of a longwall panel. The PRW intensity is also dramatically mitigated on the longwall face, and the strong dynamic load pressures resulting from the massive roof rupture are largely eliminated. The results suggest that LHF greatly promotes the caving of strong, hard-to-cave roofs behind the longwall face, which results in many favorable outcomes including a significant reduction of the periodic roof weighting (PRW) interval and likelihood of a long PRW duration. Comprehensive monitoring was performed to monitor the generated hydraulic fractures, mining-induced pressure, periodic roof weighting, and microseismic events. #Snappy 70m series ggv trialIn this study, a field trial was carried out involving large-scale hydraulic fracturing (LHF) to weaken strong, hard-to-cave rock strata above a longwall panel in an underground coal mine. Roof strata control is crucial to production safety in underground coal mines. The simulation method gives a valuable insight into the disturbance effects and focal mechanism of mine tremors. The research results provide a useful reference for understanding the mechanisms of rockburst induced by mine tremors. The disturbance to the roadway is largest in the direction of 45° of the fault plane. The effects of tremor disturbance intensity are studied based on the relationship between the relative spatial orientation of the roadway and fault plane. #Snappy 70m series ggv crackMuch interesting information is studied in detail, including the characteristics of the source radiation wave field, the variation of the stress field caused by seismic wave diffusion, and the changes in stress, crack and displacement throughout the process of the roadway rockburst from inoculation to explosion under the disturbance of seismic waves. In this paper, based on the engineering background that strong mine tremors frequently occurred in the 7301 working face of the Baodian coal mine due to thick-hard stratum fracture, a novel method is used to successfully simulate the whole process of tremor generation caused by thick-hard roof fracturing and triggered rockburst in a roadway. Mine tremors and rockbursts triggered by thick-hard roof fracturing are major problems in safe production of coal mines, and the corresponding numerical simulation is also a great challenge due to complexity of rock failure and wave field characteristics radiated from sources. The more competent the main roof, the lower the maximum permeability. The greater the horizontal-to-vertical stress ratio, the lower the maximum permeability. The permeability increases as fracturing and collapse of rock mass within the region and then decreases as the collapsed rock mass compacts. The permeability of a given region in the fractured zone can be evaluated by measuring the area of the voids and fractures within the region. The rock bridge forms and ruptures periodically as longwall mining proceeds. It is found that periodic weighting does not just involve the local immediate and main roof that composes a cantilever beam right behind the longwall face, it may also involve the rupture of a rock bridge in the overburden strata above the fractured zone. Both the physical and numerical model successfully captured periodic weighting as the longwall face advances. A numerical model was then created according to the geological and geotechnical conditions of the physical model. In this study, a physical model was initially created to produce the process of longwall mining with great attention focused on the caving and fracturing process of the overburden strata. Knowledge of the extents and characteristics of the fractured zone is important to evaluating many mining-induced issues including abutment pressure relief, methane production, and ground subsidence prediction. The overburden rock strata fractures and collapses as the extraction of a longwall panel. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |