The permeability of closely placed blocks on gravel

The permeability of a layer of closely placed concrete blocks on a sublayer of gravel or sand with or without a geotextile has been investigated. The results indicate that the permeability of the blocks can be described as a combination of the permeability of the joints and the permeability of the gravel just below the blocks. The permeability of the joints can be described with well known hydraulic formulas for the pressure drop due to a sudden contraction and for the influence of wall friction. The influence of the gravel is described by formulas used in groundwater flow computations. In the paper it is shown that a combination of these formulas leads to a permeability formula that agrees well with the results of permeability tests.