Linking particle stress distributions in clogged silos and the avalanche size

Abstract Discrete bodies passing through narrow openings in silos can become clogged, forming a quasi-static assembly whose stress state reflects the preceding discharge process. Although central to clog stability and unclogging, this stress state does not fully follow either Janssen-type or hydrostatic models, suggesting history-dependent mechanics. Here we show that stress decreases with opening size through the number of particles released before clogging, defined as the avalanche size. Scaling analysis identifies two transitions, with stress resembling that of sealed bodies below a minimum avalanche size but approaches a minimum asymptotic value as avalanche size increases. This decrease is accompanied by reduced effective particle weight and increased sidewall shear support. Boundary force chains orient toward silo walls, while central clogging arches increase the normal-to-parallel stress ratio along force-chain directions, leading local stress to decrease with depth. This study provides insights into the mechanisms underlying stress variations in particle assemblies clogged above openings.