ASDSO Dam Safety Toolbox

Foundation Mapping

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The foundation of a dam serves as the crucial base upon which the entire structure relies for stability and safety. Foundation mapping plays a vital role in dam construction by providing detailed information about the geological bedrock beneath the proposed site.


Foundation mapping aims to understand both the geological and geotechnical characteristics of the site where a dam will be constructed. It involves the collection and analysis of data on the composition, structure, and properties of the underlying bedrock. Overall, the purpose is to assess the suitability of the foundation for dam construction. By identifying potential hazards, such as weak zones, fault lines, or unstable rock formations, engineers can make informed decisions and implement appropriate measures to ensure the dam's stability and longevity.


Data collection for foundation mapping employs various. Geophysical surveys, which include seismic refraction and electrical resistivity tests, provide valuable insights into the subsurface structure and properties. Borehole drilling and sampling allow engineers to examine the composition and stability of the rock strata directly. Laboratory testing on collected samples helps determine their strength, permeability, and other important properties. A combination of these methods helps engineers develop a comprehensive understanding of the foundation conditions.


Foundation mapping also enables engineers to evaluate the potential challenges associated with dam construction such as potential instability factors or geological faults, which may pose risks to the dam's integrity. By assessing these risks, engineers can develop appropriate design strategies and select suitable construction methods to mitigate the identified hazards.


Foundation mapping findings significantly influence the design considerations and mitigation measures for dam construction. The data obtained from mapping studies guide decisions related to dam alignment, excavation methods, foundation treatment, and anchoring systems. Design parameters, such as dam height, spillway location, and foundation reinforcement, are influenced by the geological and geotechnical conditions revealed through foundation mapping. Properly addressing these considerations ensures the long-term stability and safety of the dam.


Foundation mapping is not a one-time activity; it is an ongoing process that continues throughout the life cycle of the dam. Monitoring systems are installed to assess the behavior and performance of the foundation and the dam structure over time. Real-time monitoring allows for the detection of any changes or movements in the foundation, enabling timely interventions and adaptations. Regular monitoring helps ensure that the dam remains safe and reliable in the face of evolving geological conditions.

Best Practices Resources

Construction Project Geotechnical and Materials Completion Report for Major USACE Projects (ER 1110-1-1901 ), USACE