Prior to the design phase, reconnaissance and feasibility studies should be performed at the proposed dam site to understand the regional geology and properly characterize the site conditions as they relate to stability. Such studies should be conducted by an experienced engineering geologist with training in dam stability. A complete understanding of the geologic conditions is critical to the evaluation of dam site selection, feasibility, and stability as well as selection of the dam type and configuration. In addition, constructability and costs are directly related to the geologic conditions, particularly the potential need for mitigation of seepage and/or stability concerns.
In seismically active regions, the construction of a berm or buttress on the upstream or downstream slope may be required to increase the factor of safety against seismically induced stability failures, sliding, and settlement due to strength reductions from shaking and liquefaction.
Improper foundation preparation resulting from a lack of geologic consideration can lead to dam failure by a variety of modes including differential settlement, slope instability, sliding, uplift pressures, uncontrolled foundation seepage, internal erosion, shearing, and faulting.
Revision ID: 5594
Revision Date: 12/14/2022