Trapdoor model test and DEM simulation associated with arching

M Otsubo and R Kuwano and U Ali and H Ebizuka, PHYSICAL MODELLING IN GEOTECHNICS, VOL 1, 233-238 (2018).

The estimation of earth pressure exerted on underground structures is not easy due to complex interactions between soil and structure. The distribution of earth pressure varies with differential settlement of soils around the structure. This contribution assesses evolution of earth pressures acting on an embedded structure caused by differential settlement. A soil box with five base platens, that can be lowered or uplifted separately, was developed to undertake trapdoor tests. A series of trapdoor tests was conducted to quantify earth pressures acting on the base platens while varying the burial depth and the density of Toyoura sand. The earth pressure was measured using load cells located inside each base platen. Similar test condition was considered in equivalent discrete element method (DEM) simulations in which spherical particles analogue to soil grains were used. The DEM results capture the deformation characteristics of the ground and the pressure distribution on the bottom platens observed in the model tests. The evolution of strong contact forces during lowering the trapdoor was analysed and development of an arch above the lowering trapdoor was confirmed.

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