Numerical simulation of percolation box experiments on the performance of a richards barrier

摘要

A Richards Barrier is composed of a fine porous material overlying a coarse porous material with an interface between the two that is sloped.Water percolating downward is prevented from entering the coarse material by capillary forces,and is diverted laterally along the sloped interface.A Richards Barrier is proposed as a flow diversion barrier system to prevent water from dripping onto waste canisters in the potential HLW repository at Yucca Mountain~1,2. Flow diversion using a Richards Barrier relies upon unsaturated conditions,a large contrast in pore size between the two layers,an interface slope,and sufficiently high hydraulic conductivities of the upper layer.previous analyses have shown that a Richards Barrier is capable of diverting large vertical uniform infiltrations~3,4. A series of laboratory Percolation Box tests were performed~5 and confirmed the flow diversion capability of a Richards Barrier under high point source flow conditions.To further evaluate use of a Richard Barrier in the repository at Yucca Mountain,numerical simulations of the Percolation Box texts were conducted.This paper reports the findings from the simulation work.