Subsidence Prediction of Overburden Strata and Surface Based on the Voussoir Beam Structure Theory

Abstract

The hard and stiff strata (key strata) bear the overburden load in the form of a voussoir beam structure (VBS) after break. The VBS affects both the surface subsidence and the stope underground pressure. Therefore, the reasonable method to predict the surface subsidence is based on the whole subsidence formulae of the VBS. This study first establishes the subsidence formulae of the VBS analytically. The influence of the block length on the subsidence curve and the VBS level on the zero-subsidence range are then analyzed based on the subsidence formulae of the VBS. The results show the half-subsidence curve of the VBS is an S-shaped curve. The block length hardly affects the S-shaped subsidence curve determined by the width of the undercompacted zone. Furthermore, a greater undercompacted zone width corresponds to a greater offset distance of the inflection point. The higher the VBS level, the farther the zero-subsidence range, and the flatter the subsidence curve. The subsidence of the highest VBS can approximately represent the surface subsidence when the topsoil is thin enough.

Study on the movement characteristics of the overlying stratum and surrounding rock control in ultraclose coal seams: A case study

“…Mining activity at a single longwall face in the UCS will cause destruction of the old roof stratum following a vertical "O-X" pattern, after which a "masonry beam" structure will form in the overlying stratum. [26][27][28][29][30][31] As demonstrated by a considerable number of studies, [31][32][33][34][35][36][37] the mining activities at multiple longwall faces will enlarge the fracture zone of the overlying stratum when the coal seam is deeply buried. In this case, the key layers located in the upper middle part of the fracture zone far away from the coal seam may experience rotation or fracturing and become unstable.…”

Failure mechanism and fracture aperture characteristics of hard thick main roof based on voussoir beam structure in longwall coal mining

“…using various methods, including theoretical research, [10][11][12] in situ investigation, [13][14][15][16] and physical and simulation analysis. [17][18][19][20][21][22] On the basis of spatial structure evolution and load conditions, analyses typically simplify the unit thickness on the working face middle to a beam model, [23][24][25][26] such as clamped beam, simply supported beam, and voussoir beam; the voussoir beam approach is a kind of structure widely used and was developed rapidly. These studies on the structural model of the main roof overlying strata often model the rock beam as a continuous medium and then analyze the stability and failure of the rock beams.…”

Influence Law of Interbedded Strata and Their Collapse on the Mining of Extremely Thick Coal Seam under Goaf

“…Yan [14][15][16][17] conducted a preliminary study on the joint mining theory of short-distance thin coal seams; Zhu et al [18] conducted a relevant theoretical investigation with the following assumption: the interlayer and upper degraded rock formation were regarded as a block and a loose body, respectively. Due to the variation of coal seam occurrence conditions and interlayer distance, the mine pressure performance of the fully mechanized coal mining face has various characteristics [19][20][21][22][23][24]. Under this condition, it is difficult to determine the load of working faces simply based on the traditional theory of roof support and control.…”