Investigation on the packing behaviors and mechanics of Li4SiO4 pebble beds by discrete element method

Under the operating condition of a solid breeding blanket, the ceramic breeder pebbles applying pebble bed configuration will conduct with complex mechanical behaviors. In this study, the Discrete Element Method (DEM) was adopted to generate randomly packed pebble beds considering the size distribution, particle sphericity and surface friction of breeder pebbles. Based on these discrete packing structures, the cyclic uniaxial compression tests (UCTs) were implemented in the mechanical analysis of the pebble beds. The results indicate that the initial packing behaviors and non-linear stress-strain responses of the pebble beds were highly affected by size distribution, particle sphericity and surface friction of breeder pebbles. Besides, the internal contact forces between the pebbles could be alleviated to some extent through cyclic uniaxial compression tests. After these progressive loading cycles, the pebble beds were strengthened with increasing effective elastic moduli, and the effects of the loading pressure on the elastic moduli of the strengthened pebble beds were estimated.