The research background is the hidden danger of dynamic impact disaster caused by large-scale collapse of surrounding rock in the isolated large goaf area of Dongshengmiao Mine, a coupled impacting mechanical model related to a caving rock-air-surrounding rock system is established by using the aerodynamic theory and the energy conservation theory. An exponential relationship between cushion thickness and impacting force is formed by applying several theoretical methods. Under the impacting load, the calculating formulas of maximum tensile stress, shear stress and deflection are derived by applying the material mechanics theory. Furthermore, based on the theoretical derivation formula, the reasonable thickness of cushion is studied quantitatively in the super-large goal and the correctness of the theoretical results is verified by FLAC3D numerical simulation. The results show that: (1) Considering the influence of compressed air and surrounding rock friction on the motion of caving rock mass, the maximum impacting velocity of falling body rolling to bottom of goaf is solved as a result of 30.99 m·s-1. (2) The buffering effect gradually decreases with the increasing cushion thickness, namely it hardly produces cushioning effect when the thickness of cushion increases to a certain value. (3) Compared with the fixed beam, the maximum tensile stress, maximum shear stress and maximum deflection solved by simply supported beam are closer to the numerical simulation results from the ore pillar, and the optimum cushion thickness is 18 m.
Dong Chuanlong
,
Zhang Fei
,
Teng Teng
,
Lei Lixing
. Reasonable Thickness Research of Buffer Cushion under the Impaction of Extra Large Caving Body[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 881
-891
.
DOI: 10.20174/j.JUSE.2024.S2.43
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