Mechanical properties and energy dissipation law of saturated coal samples under dynamic loading

Abstract

To investigate the mechanical properties and energy variation characteristics of saturated coal samples under dynamic loading, a 50 mm diameter split Hopkinson rod device (SHPB) was used to conduct impact loading tests on both saturated and natural coal samples, and to analyze influence of water content on the dynamic strength, strain, damage, and energy transfer efficiency of coal samples. The results show that within the strain rate range of 14.25 s−1 to 59.57 s−1, water has a dual effect on the dynamic strength of coal samples, manifested as low strain rate weakening and high strain rate strengthening; under the same impact load, there is a significant difference in deformation between natural coal and saturated coal, with a maximum strain difference of 38.46%; the water content of coal samples significantly affects the energy transfer efficiency, where the energy consumption density of both natural and saturated coal samples increases linearly with incident energy, and the energy reflectance of natural coal is more than that of saturated coal, and the transmittance of natural coal is less than that of saturated coal, and the dissipation rate is approximately equal.

Keywords

• hydraulic fracturing
• saturated coal sample
• dynamic loading
• mechanical properties
• energy dissipation
• impulsive load