ASDSO Dam Safety Toolbox


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Figure 15.1.2-1 Overview of Grouting Operations at Ridges Basin Dam[1]

(Image Source: USACE)

"Grouting in civil works activities is performed as: (1) an element of permanent construction, (2) a post-construction remedial treatment, or (3) an element of expedient construction or repair. Examples of permanent construction are curtain grouting in foundations for dams and ground stabilization of foundation materials for large buildings. Examples of post-construction remedial treatment include grouting voids under concrete structures and reducing leakage through dam foundations or abutments. Grouting is used for both temporary and permanent treatments. It should be considered in combination with other appropriate types of treatment for best results. Other types of treatment may include excavation, compaction, concrete cutoff walls, slurry trenches, impervious blankets, drainage blankets, and filter zones. Treatments also include relief wells, drilled drains, sheet pile cutoff, dental concrete, drainage tunnels and galleries, underpinning, and structural foundations. Purposes of expedient grouting include repair of roadways, cofferdams, and stability and groundwater control during construction."[2]

"Grouting is the process in injecting liquids, mixed suspensions, or semi-solid mixtures under pressure to achieve one or more desirable end results in terms of improving engineering properties. To accomplish this, the injected grout must eventually form either a gel or a solid within the treatment zone. Permeation grouting is the injection of high-mobility grouts (HMGs) into small voids within soil or rock masses, into small voids between these materials and an existing structure, and/or into small cracks or fractures within structures themselves. Void-filling grouting involves using low- (or limited) mobility grout (or grouting) (LMG) or other materials having properties suitable for effective filling of large voids. Compaction grouting is the injections of plastic, semi-solid mixtures to densify or displace deformable materials. In-situ modification or replacement includes specialized techniques such as a jet grouting or hydrofracture grouting... Depending on the specific application, grouting is used as either the primary or sole means of effecting property improvement, or it may be used in conjunction with other technologies and methods."[2]

"Grouting is commonly used to reduce permeability, which might be necessary for reducing rates of seepage or leakage through or into new or existing structures and foundations, reducing hydrostatic forces acting on structures, altering flow gradients or flow paths to achieve specific design objectives, inhibiting internal erosion of foundation and embankment materials, and/or controlling water for excavations as required to facilitate dewatering or excavation stability. In any critical hydraulic application, grouting is normally one of several lines of defense."[2]

Typical Applications of Grouting for Dams and Lock Structures

  • "Hydraulic barrier grouting to control leakage and pressure distributions (i.e., grout curtain construction)
  • "Foundation consolidation grouting to reduce foundation and structure deformations under load
  • "Contact grouting of the interface between structures and foundations
  • "Void filling in foundations beneath structures
  • "Compaction grouting for densification of loose deposits or jet grouting to replace zones of loose materials
  • "Pre-treatment of fractures rock foundations to enable cutoff wall construction
  • "Grouting of leaking cracks or joints in structures
  • "Abandonment or backfilling of exploration and instrument holes
  • "Improvement of zones as required to facilitate dewatering and/or excavation stability[2]

Best Practices Resources

Design Standards No. 13: Embankment Dams (Ch. 15: Foundation Grouting), USBR

Design of Small Dams, USBR


On-Demand Webinar: Introduction to Grouting for Dams


Revision ID: 7286
Revision Date: 07/18/2023