On the mechanism of the formation of horizontal cracks in a vertical column of saturated sand

Extended horizontal cracks have! been observed experimentally in a vertical column of saturated sand when a flow of water is forced to percolate upwar d through it. This paper provides a theory for this phenomenon. It will be shown that the presence of inhomogeneity in permeability along the length o f the column is essential for such cracks to develop. It will also be shown that small initial inhomogeneity may be magnified through the transport of the finer component of the sand by percolation. Under certain conditions l iquefaction takes place at a section of the sand column causing a crack to initiate and grow there. This theory is found to be in good qualitative agr eement with the experimental findings.