Sliding Stability: Difference between revisions

Latest revision as of 20:48, 11 July 2023

Learn from the failure of Bayless Dam due to instability at DamFailures.org

"Stability must be assessed on selected surfaces within the structure... Sliding safety must also be assessed at/or near the foundation-structure interface. This surface may be either level or sloping. Generally, it may by assumed that a surface that slopes upward (in the direction of possible sliding) will have a beneficial effect, while one that slopes downward will increase the possibility for sliding... Where a shallow weak seam exists below a structure's contact with the foundation, or a structure is imbedded below the top of the foundation, two possible failure modes are present. One mode involves slippage along the weak plane directly under the structure plus slippage along a plane through the foundation above the weak seam (crossbed shear for rock or passive resistance for soil). When the weak seam extends a large distance past the toe of the structure without daylighting, the second mode will usually be critical."^[1]

Examples

Learn from the failure of Bayless Dam due to instability (DamFailures.org)

Best Practices Resources

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

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

Design of Small Dams, USBR

Sliding Stability for Concrete Structures (ETL 1110-2-256), USACE

Trainings

On-Demand Webinar: Stability Evaluations of Concrete Dams

On-Demand Webinar: Introduction to Concrete Gravity Dams

Citations:

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

Revision ID: 7169
Revision Date: 07/11/2023

[EM_1110-2-2100-1] Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE, 2005

[1]

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 <!-- Introductory paragraph or topic page summary -->
-"A proper [[stability]] analysis cannot be performed without knowing the potential planes of weakness beneath the structure, the strength of the materials along potential planes of weakness, uplift forces that occur on the structure or on planes of weakness, the strength of backfill materials, and all loads and load conditions to which the structure may be subjected. Knowledge of geologic formation beneath the structure is also important in defining seepage conditions and uplift pressures. Without adequate foundation explorations and testing, the safety factors provided to assess stability of the structure are meaningless. Preliminary stability analyses are useful to identify design parameters, which require special attention. In some rock foundations there may be many faults, shear zones, and discontinuities that make it impossible to do little more than predict average shear and cohesive strengths of the materials that make up the foundation. Use of lower bound values for foundation shear strength or upper bound values for loads is only acceptable when it can be demonstrated that the added costs to improve the accuracy of the strength and loading data will not lead to significant savings for the structure or foundation."<ref name="EM 1110-2-2100">[[Stability Analysis of Concrete Structures (EM 1110-2-2100) | Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE, 2005]]</ref>
+"[[Stability]] must be assessed on selected surfaces within the structure... Sliding safety must also be assessed at/or near the foundation-structure interface. This surface may be either level or sloping. Generally, it may by assumed that a surface that slopes upward (in the direction of possible sliding) will have a beneficial effect, while one that slopes downward will increase the possibility for sliding... Where a shallow weak seam exists below a structure's contact with the foundation, or a structure is imbedded below the top of the foundation, two possible failure modes are present. One mode involves slippage along the weak plane directly under the structure plus slippage along a plane through the foundation above the weak seam (crossbed shear for rock or passive resistance for soil). When the weak seam extends a large distance past the toe of the structure without daylighting, the second mode will usually be critical."<ref name="EM 1110-2-2100">[[Stability Analysis of Concrete Structures (EM 1110-2-2100) | Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE, 2005]]</ref>
-"Stability must be assessed on selected surfaces within the structure... Sliding safety must also be assessed at/or near the foundation-structure interface. This surface may be either level or sloping. Generally, it may by assumed that a surface that slopes upward (in the direction of possible sliding) will have a beneficial effect, while one that slopes downward will increase the possibility for sliding... Where a shallow weak seam exists below a structure's contact with the foundation, or a structure is imbedded below the top of the foundation, two possible failure modes are present. One mode involves slippage along the weak plane directly under the structure plus slippage along a plane through the foundation above the weak seam (crossbed shear for rock or passive resistance for soil). When the weak seam extends a large distance past the toe of the structure without daylighting, the second mode will usually be critical."<ref name="EM 1110-2-2100"/>
 ==Examples==
@@ Line 18: / Line 16: @@
 ==Best Practices Resources==
-{{Document Icon}} [[Stability Analysis of Concrete Structures (EM 1110-2-2100)|Stability Analysis of Concrete Structures (EM 1110-2-2100) (U.S. Army Corps of Engineers)]]
+{{Document Icon}} [[Stability Analysis of Concrete Structures (EM 1110-2-2100) | Stability Analysis of Concrete Structures (EM 1110-2-2100), USACE]]
-{{Document Icon}} [[Sliding Stability for Concrete Structures (ETL 1110-2-256)|Sliding Stability for Concrete Structures (ETL 1110-2-256) (U.S. Army Corps of Engineers)]]
+{{Document Icon}} [[Gravity Dam Design (EM 1110-2-2200) | Gravity Dam Design (EM 1110-2-2200), USACE]]
-{{Document Icon}} [[Gravity Dam Design (EM 1110-2-2200) | Gravity Dam Design (EM 1110-2-2200), USACE, 1995]]
+{{Document Icon}} [[Design of Small Dams | Design of Small Dams, USBR]]
-{{Document Icon}} [[Design of Small Dams | Design of Small Dams, USBR, 1987]]
+{{Document Icon}} [[Sliding Stability for Concrete Structures (ETL 1110-2-256) | Sliding Stability for Concrete Structures (ETL 1110-2-256), USACE]]
 ==Trainings==