ZHU C X，HUO J X，WU D Z．Study on dynamic mechanical properties and numerical simulation of fractal coal-rock cement［J］.Journal of Henan Polytechnic University( Natural Science) ，doi:10.16186/j.cnki.1673-9787.2024030053

doi:10.16186/j.cnki.1673-9787. 2024030053

Received：2024-03-19

Revised：2024-06-21

Online：2024-08-20

Study on dynamic mechanical properties and numerical simulation of fractal coal-rock cement

ZHU changxing，HUO Jiaxin，WU Dazhi

School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000,Henan, China

Abstract: [Objective]In order to study the influence of particle breakage degree on the dynamic mechanical properties of coal-rock cemented body, [Methods] Based on the theory of solid particle distribution in loose medium, loose coal with different crushing degree was prepared with fractal dimension of 1.4, 1.7, 2.0, 2.3 and 2.6 respectively, and the cementing material was mixed with the coal body in proportion to make standard block after curing. The split Hopkinson pressure bar(SHPB)impact test was carried out, and the finite element software LS-DYNA was used to simulate the SHPB test process. [Results] Experimental results: The compressive strength is the lowest when the fractal dimension is 1.7 and the highest when the fractal dimension is 2.6. The dynamic mechanical properties of coal and rock samples are greatly affected by the degree of coal fragmentation. The internal energy of cement matrix is much greater than the sum of the internal energy of coal with four particle sizes. The numerical simulation results of peak stress, strain and failure mode agree well with the experimental results. Results indicate: In the particle size range of 0~20 mm, the overall strength of the test block is higher when the proportion of small particles in the range of 0~5 mm is higher. The dynamic compressive strength of cement decreases first and then increases with the increase of fractal dimension. The dissipative energy of the test block also decreases first and then increases under dynamic compression. The media gradation with fractal dimension 1.7 is not conducive to the mechanical properties of the cement block. As the main energy storage medium, the cement matrix bears the main energy absorption and dissipation. The reasonable selection of HJC parameters can make the numerical simulation reflect the dynamic mechanical characteristics of the test block. [Conclusion] The research results can provide some technical support for the subsequent grouting of coal and rock.

Key words: coal crushing degree; cement body; Split Hopkinson Pressure Bar; dynamic compressive strength; numerical modeling

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