Abstract
Ensuring the stability of paste false rooves is an important issue in the study of the process of paste filling and slicing mining. Here, a mechanical model of a paste false roof is created to analyze its stability in the process of lower slicing mining in order to determine the minimum slicing thickness of the false roof. We use FLAC3D to simulate and analyze the influence of changes in paste false roof thickness on the stability of the roof. The quantitative functional relationship between the thickness and the subsidence of a false roof, and the optimal thickness of the artificial paste roof, is finally obtained by the development law of the plastic zone in the lower slicing face. The results show that when the thickness of the paste false roof is 3.2 m, the roof can maintain its self-stabilization state and ensure the normal mining of lower layers. Because the same thickness of the upper and lower layers is beneficial for mining replacement and equipment selection in different layered working faces, the optimal thickness of a paste false roof is determined to be 3.2 m.
Highlights
Paste filling mining can effectively control surface deformation and overlying rock movement and has become one of the most important technical means to recover coal resources under buildings [1]
It can be seen from the stress expressions (20)–(22) that in a long beam whose length is far greater than its thickness, the bending stress σx is of the same order as q(L/h)2, which is the main stress; the shear stress τ xy is the same as q(L/h
Breaking of the false roof is caused by shearing force: If the maximum bending stress on the beam reaches its maximum value on the neutral axis at y = 0, omitting the high-order infinitesimal terms, :max =
Summary
Paste filling mining can effectively control surface deformation and overlying rock movement and has become one of the most important technical means to recover coal resources under buildings (structures) [1]. The existing research mainly analyzes the stability of the false roof as it relates to the backfill, regarding aspects such as the amount of underfilling, the compression rate of the filling, the filling rate, the mining method, and the overburden load [11,12]. Under some mining geological conditions, to effectively control surface deformation, recover the “three-under” compressed coal resources, and digest gangue to protect the Sustainability 2021, 13, 10899. According to the mining geological conditions of the Gaohe Coal Mine, the paste filling layered coal mining method is selected to recover coal resources. Theoretical analysis combined with numerical simulation is applied to study the relationship between the thickness of the paste false roof and the stability of the false roof
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