Short-wall paste continuous mining and continuous backfilling for controlling industrial square surface subsidence

Abstract

To facilitate coal mining under the industrial square in Western China, short-wall paste continuous mining and continuous backfilling (PCMCB) is proposed to release the overlaid resources and handle coal gangue. First, the concept of short-wall PCMCB is presented, and the principle of surface subsidence is analyzed. Second, the mechanical model of the branch roadway and strength of the backfill body are established via mechanical derivations. Third, the proportion of backfill materials is calculated. Finally, field applications are carried out in the Dingjiaqu coal mine. The results show the following: 1) Based on the simply supported beam model of the roof and strength design model of the backfill body, the reasonable width of the branch roadway was determined as 5 m and late strength of the backfill body should exceed 2.62 MPa in the Dingjiaqu coal mine. 2) According to the design strength of the backfill body and backfill material proportion, the reasonable ratio of cement: fly ash: gangue: water was determined as 1:1.82:4.17:1.78. 3) In accordance with the equivalent mining height theory, the critical filling rate of the goaf should be more than 90% to ensure that the deformation is within the first level of building damage. 4) The field application shows that subsidence could be effectively controlled by backfilling, the overall surface subsidence was very small, and the maximum subsidence value (77 mm) was far lower than the deformation extremes of the building protection requirements. This study provides practical guidance for the exploitation of overlaid resources under similar shallow burial conditions, which can help in the disposal of coal gangue with considerable social and economic benefits with popularization and application.

Coal and Rock Dynamic Disasters: Advances of Physical and Numerical Simulation in Monitoring, Early Warning, and Prevention - Volume II

“…Chen and Su, 2019 analyzed the features of harmful gases in tunnels and drew upon experiences and data from similar underground projects in geochemically comparable areas to provide a reference for studying harmful gases in metamorphic and magmatic rock areas. Lastly, Huo et al (2023) applied the key stratum theory, fluid mechanics, and other theories to propose conditions for the failure of harmful gases in Jurassic goaf and establish a multi-parameter control equation for harmful gas discharge from Jurassic goaf to the coal seam working face.…”

“…The classification standard for the risk of mud and debris flow refers to the standards used for the Wenchuan debris flow, as shown in Table 9. According to the current urban area range of Yunlong County and the overall development plan (2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023)(2024)(2025)(2026)(2027)(2028)(2029)(2030), the urban area of Yunlong County is approximately 2.5075 square kilometres. Based on the qualitative evaluation and FLO-2D numerical simulation results, a risk assessment was conducted for geological hazards in the urban area of Yunlong County before and after geological disaster management.…”