Assessment of Seismic Stability of Dolphin Pool Slope of John Hart Dam

The John Hart Dam is in a high seismic risk area. To ensure dam safety, the Dolphin Pool Slope portion of the dam had to be rebuilt. Extensive field investigations and laboratory testing were conducted to obtain representative soil strength parameters for seismic stability analyses and rehabilitation design. Back analysis of the performance of the Dolphin Pool Slope under a 1946 earthquake loading confirmed the strength parameters determined from the field investigation and laboratory testing. Seismic analyses indicated that large zones of the dam could be expected to liquefy under the Maximum Credible Earthquake and, because of uncertainties regarding the residual strengths of sand layers, remedial measures were required which involved the removal and rebuilding of the Dolphin Pool Slope with compacted granular fill