Internal Stability (Stresses): Difference between revisions

Revision as of 18:02, 14 December 2022

Learn more about the need to consider uplift pressure when designing a gravity structure at DamFailures.org

Internal stability failures occur at individual joints, lift surfaces, or other weak planes internal to a dam structure rather than the structure as a whole. This may include sliding on lift surfaces or exceedance of allowable material strengths. ^[1]

Examples

Lesson learned: Concrete gravity dams should be evaluated to accommodate full uplift (Damfailures.org)

Case study: Oroville Dam Spillway Incident (Damfailures.org)

Case study: St. Francis Dam Failure (Damfailures.org)

Best Practices Resources

Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE, 2005

Gravity Dam Design (EM 1110-2-2200), USACE, 1995

Arch Dam Design (EM 1110-2-2201), USACE, 1994

Design of Small Dams, USBR, 1987

Trainings

On-Demand Webinar: Introduction to Concrete Gravity Dams

On-Demand Webinar: Uplift and Drainage for Concrete Dams and Spillways

On-Demand Webinar: Analysis of Concrete Arch Dams

On-Demand Webinar: Stability Evaluations of Concrete Dams

On-Demand Webinar: Roller Compacted Concrete - Design and Construction of Water Control Structures

Citations:

↑ Stability Analysis of Concrete Structures (EM 1110-2-2100) (U.S. Army Corps of Engineers)

Revision ID: 5698
Revision Date: 12/14/2022

[EM2100-1] Stability Analysis of Concrete Structures (EM 1110-2-2100) (U.S. Army Corps of Engineers)

[1]

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 | [[Image:GravityDamUplift1.png|350px|x350px|link=https://damfailures.org/lessons-learned/concrete-gravity-dams-should-be-evaluated-to-accommodate-full-uplift/]]
 |-
-|style="text-align:center; font-size:90%;"| Learn more [[about]] the need to consider uplift pressure when designing a gravity structure at [https://damfailures.org/lessons-learned/concrete-gravity-dams-should-be-evaluated-to-accommodate-full-uplift/ DamFailures.org]
+|style="text-align:center; font-size:90%;"| Learn more about the need to consider uplift pressure when designing a gravity structure at [https://damfailures.org/lessons-learned/concrete-gravity-dams-should-be-evaluated-to-accommodate-full-uplift/ DamFailures.org]
 |}
 <!-- Introductory paragraph or topic page summary -->
-"Water pressures caused by reservoir water and tailwater occur within the dam and foundation in pores, cracks, joints, and seams. The distribution of internal water pressures along a horizontal section through the dam or its foundation is assumed to vary linearly from full reservoir pressure at the upstream face to zero or tailwater pressure at the downstream face in the absence of drains or a more detailed analysis."<ref name="Small Dams">[[Design of Small Dams | Design of Small Dams, USBR, 1987]]</ref>
+Internal [[stability]] failures occur at individual joints, lift surfaces, or other weak planes internal to a dam structure rather than the structure as a whole. This may include sliding on lift surfaces or exceedance of allowable material strengths. <ref name="EM2100">[[Stability Analysis of Concrete Structures (EM 1110-2-2100)|Stability Analysis of Concrete Structures (EM 1110-2-2100) (U.S. Army Corps of Engineers)]]</ref>
-"The internal water pressure, also called uplift, acts to reduce the compressive stresses normal to a horizontal section through the dam. Including a line of vertical formed drains within the dam and parallel to the upstream face serves to reduce the uplift force. The uplift reduction is dependent on the size, location, and spacing of the drains.<ref name="Small Dams"/>
-"Forces from water pressures also occur within the foundation. Uplift forces in the foundation decrease the normal forces occurring on potential sliding planes. Water forces occurring on high angle joints increase driving forces on foundation blocks. Both of these reduce foundation sliding [[stability]].<ref name="Small Dams"/>
-"The uplift forces within the foundation and along the foundation-dam contact can be reduced by a line of drain holes drilled into the foundation from the floor of the foundation gallery. The internal pressure distribution through the foundation depends on depth, location, and orientation of the drains, rock permeability characteristics, jointing, faulting, and any other geologic features that may modify the flow. The line of drains should be located a distance downstream from the upstream dam face that will ensure that direct connection from the reservoir will not occur."<ref name="Small Dams"/>
 ==Examples==
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 {{Website Icon}} [https://damfailures.org/case-study/st-francis-dam-california-1928/ Case study: St. Francis Dam Failure (Damfailures.org)]
-==[[Best Practices Resources]]==
+==Best Practices Resources==
 {{Document Icon}} [[Stability Analysis of Concrete Structures (EM 1110-2-2100) | Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE, 2005]]
 {{Document Icon}} [[Gravity Dam Design (EM 1110-2-2200) | Gravity Dam Design (EM 1110-2-2200), USACE, 1995]]
@@ Line 30: / Line 24: @@
 {{Document Icon}} [[Design of Small Dams | Design of Small Dams, USBR, 1987]]
-==[[Trainings]]==
+==Trainings==
 {{Video Icon}} [[On-Demand Webinar: Introduction to Concrete Gravity Dams]]
 {{Video Icon}} [[On-Demand Webinar: Uplift and Drainage for Concrete Dams and Spillways]]