Analysis of progressive failure and cracking in old British dams

Three sections, representative of existing old puddle core embankments, were analysed using non-linear finite element techniques, They had shoulders of granular fill, puddle clay cores and strong foundations, The analyses showed that progressive failure was negligible during drained construction, operation and undrained draw-down, The cores were vulnerable to cracking if they were subjected to full reservoir pressure on their upstream boundary, However, very slow drained impounding caused mean total stresses to rise so that fracture was not indicated, Hydraulic fracture was predicted in a deep cut-off trench filled with puddle clay, Cyclic drawdown and impounding increased stresses in the upstream side of the core, so increasing the resistance to cracking, Total stresses increased and decreased with reservoir level, as has been observed in the field.