Deformation mechanism and control measures of roof deformation before filling in continuous mining and continuous backfilling quarries

Based on the mining and filling contradiction, cemented backfilling mining technology with continuous mining and continuous backfilling methods was proposed, and the deformation of the roof before filling determines the upper limit of the filling rate, which significantly affects the filling effect. Four typical distribution patterns were proposed by studying the roof’s deformation evolution law before filling, and a corresponding mechanical model was established based on the theory of elastic foundation beam. The key factors affecting the deformation of the roof before filling were analyzed. The mechanism of the roof deformation before filling was revealed, and the targeted control measures were proposed. The results show that the deformation of the roof before filling increases significantly in the two-stage filling, and it is approximately linearly distributed in the branch alley. Accordingly, the roof deformation before filling can be classified into symmetric distribution, arc-shaped distribution, and seemingly linear distribution, and thus four distribution patterns are established. The influence of load release rate and branch width on the four patterns is significant, and the deformation before the filling of neighboring branches mainly affects each other under large disturbance conditions. The surrounding rock stress release and bearing structure support lead to the symmetric distribution of roof deformation, and the over-disturbance is the main reason for the asymmetric distribution of roof deformation. The coal pillar indirectly reduces the roof deformation of even-numbered lanes by controlling the deformation of odd-numbered lanes. The filling body of odd-numbered lanes can reduce its deformation before filling deformation during the filling period of even-numbered lanes by directly controlling the roof. The combined control measures of improving the long-term strength of the first-stage filling body and the short-term strength of the two-stage filling body to shorten the proximity time and apply temporary support to reinforce the roof to inhibit subsidence are proposed to achieve effective control of the filling face in the field. The combined control measures of increasing the long-term and short-term strengths of the first-stage filling body to shorten the proximity time and applying temporary support to reinforce the roof to inhibit subsidence were proposed to achieve adequate control of the filling face in the field. The study elucidated the deformation mechanism of the roof before filling in the continuous mining and continuous filling quarry, which can provide a reference for the optimization of the process and the control of overburden deformation in similar projects.