Distribution characteristics analysis of pressure-arch in horizontal stratified rocks under coal mining conditions | Analiza karakteristika raspodjele tlaka stropa u horizontalno slojevitim stijenama u uvjetima iskapanja ugljena
The criteria of separation and dislocation of the layered roof in mining are put forward through the simplified mechanical model with weak inter-layers. Considering five different variables, namely the number of layers, the distance from the weak inter-layers to the mine opening, the thickness of the weak inter-layers, the lateral pressure coefficient and the spacing of the bedding planes, the distribution characteristics of the pressure-arch in the horizontal stratified rocks are analyzed during coal mining using FLAC3D. The results show that the newly appeared pressure-arch is composed of the original pressure-arch in each layer and the pressure-arch shape being affected by the weak layer in the surrounding rock of the mine opening. As the distance between the inter-layers and the coal seam increases, the effect on the pressure-arch is reduced gradually. The thinner inter-layers produce greater impact on the pressure-arch. The lateral pressure coefficient has a great influence on the pressure-arch and a stable pressure-arch could only be formed when the lateral pressure coefficient is in a suitable range.