抄録
Arching problems happened in cargo holds of a self-unloading ship which was newly constructed in 1991 in order to carry about 17, 000 tons of limestone. Variation of the flow properties of the cargo with time brought about an arch formation. Actually, results of shear tests for limestone under a time consolidation of 48 hours showed an increase of 120% in a flowability which was expressed by a ratio of the unconfined yield strength to the unit weight.
The critical arch span was computed from the flowability. Also the span of real arches in cargo holds was estimated from measurements of the height from the hopper outlet to the top of real arches. These results were favourably compared.
In order to eliminate arching problems of the cargo holds, an installation of a prism shaped insert having 0.774m wide by 1, 855m long was successfully tested on regular runs of the self-unloading ship.
