Dynamic Surface Subsidence Characteristics due to Super-Large Working Face in Fragile-Ecological Mining Areas: A Case Study in Shendong Coalfield, China

Table 2

Related surface subsidence parameters of some SLWF [28–34, 41].

Working face	p (%)	j (%)	Vmax (mm/d)	tanβ	S0 (m)	Displacement angle (°)	Crack angle (°)
Daliuta colliery 1203	65.0	97.0	131.8	2.6	20.4	69.7	75.3
Daliuta colliery 52304	41.2	98.0	430.0	2.9	37.5	82.0	—
Daliuta colliery 52305	40.0	98.0	617.0	2.7	39.5	83.3	88.1
Buliuta colliery 12406	—	96.0	268.0	2.5	40.0	82.5	88.5
Halagou colliery 22407	41.1	95.0	700.5	1.6	28.6	65.3	79.0
Shangwan colliery 51101	21.1	95.0	393.0	3.1	—	—	—
Buliuta colliery 31401	—	—	540.0	3.4	29.0	—	—
Hanjiawan colliery 2304	44.2	98.0	185.3	2.0	13.5	62.5	86∼87°

Note. D₁ is the transverse length of SLWF, D₃ is the longitudinal length of SLWF, h is the average mining height, C is the advance speed, H is the average mining depth, h₁ is the average thickness of aeolian sand, V_max is the maximum subsidence rate, j represents the ratio of accumulated subsidence in the active movement stage accounting for the total subsidence, p represents the ratio of the duration of the active movement stage accounting for the total movement time, tanβ represents the tangent of major influence angle, S₀ is the offset distance of the inflection point, displacement angle is the acute angle between the line connecting the critical deformation value point and the goaf edge and the horizontal line on the side of coal pillar, and crack angle is the acute angle between the line connecting the outmost ground crack outside the subsidence trough and the goaf edge and the horizontal line on the side of coal pillar.