Research on discrete element construction and parameter calibration of agglomerated particles in moist-mix shotcrete

Abstract

The purpose of this paper is to achieve the discrete element construction and contact parameter calibration of agglomerated particles in moist-mix shotcrete. The morphological characteristics and particle size distribution of Mortar-group particles (Mgp) and Aggregate-agglomerates (Aa) under different water-cement ratios are measured, the discrete element parameters of agglomerated particles and discrete element construction of various forms of particle models are clarified, and the optimal combination of contact parameters of agglomerated particles in different experimental groups are screened. The results show that the significant influencing parameters of repose angle of concrete materials under different water-cement ratios are obtained, and the second-order regression model is established between repose angle and significant parameters. The optimal combination of four significant parameters when the water-cement ratio is 0.25: the rolling friction coefficient of Mgp-Mgp is 0.15, the surface energy of Mgp-Mgp is 0.96 J·m⁻², the static friction coefficient of Mgp-SP (Steel plane) is 0.56, and the surface energy of Aa-Aa is 2.30 J·m⁻². The relative errors of average repose angles between simulation and actual physical experiments are about 2.0 %. Validation test results indicate that the discrete element construction and contact parameter combination of agglomerated particles have strong reliability, which can provide a basis for particle model construction and contact parameter support for long-distance pneumatic conveying characteristics of moist-mix shotcrete.