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Abstract In order to understand the mechanism of the underground engineering disaster caused by sand and water loss in water-rich sand stratum，a new visualization experimental device was developed to investigate the leaking process of sand and water. Five types of sands with the coarser particle size D90 between 0.4 mm and 4.1 mm were experimentally studied. A critical width of gap in the leaking process of sand and water was discovered. Numerical simulation was performed using the particle flow code-comutational fluid dynamics(PFC-CFD) method in order to study the variation of the chains of contacted force and the structure load on both sides of the gap. The results showed that catastrophe failure occured when the gap width exceeds the critical gap width. The failure surface near the gap was found to be quadratic. With the increase of the gap width，the volumetric content of sand in the discharge increased. The leaking process of sand and water accompanied a continuous and variable process of soil arch formation and break. The fluctuation of structure load on both sides of the gap reflects the forming and breaking of soil arches.
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Received: 21 October 2013
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2014, Vol. 33 
