2018-01-30_REVISION - M1977342

• Permit No: M1977342
• IBM Index Class Name: Revision
• Doc Date: 1/30/2018
• Doc Name Note: Request for TR
• Doc Name: Request for Technical Revision
• From: Climax Molybdenum
• To: DRMS
• Type & Sequence: TR29
• Email Name: PSH
• Email Name: WHE
• Media Type: D
• Archive: No

A.MW
Henderson 3 Dam Buttress Design
January 26, 2018
Page 9
Results
The 3D model resulted in the post -earthquake factors of safety summarized in Table 3 and on
Figures 14 through 17 for Stage 1 and Stage 4 buttresses. These sections and profiles are provided
to illustrate the shape of the three-dimensional failure surface. The contours indicate that the failure
mechanism engages the majority of the stepback slope, extending from the dam crest to the toe, and
nearly to the left and right abutment contacts on Section 2 and 4a areas.
Table 3: Summary of FOS Results, Post -Earthquake Stability Review with Buttress
Construction
Stage
Crest Elevation
M
213 Factor of
Safety
3D Factor of
Safety
3D Stability
Figure
1
8,883
1.1
1 A
14-15
4
8,900
1.1
1.25
16-17
3 -Dimensional Dynamic Deformation Analyses
Dynamic deformation analysis was performed for the Stage 1 and 4 with crest height elevation of
8,883 feet and 8,900 feet to evaluate if tolerable deformations occur after the design MDE event.
Three-dimensional post -earthquake dynamic deformation analyses were performed with the
computer code FLAMD, Version 5.01 (Itasca, 2011), a 3D explicit finite difference code. The
dynamic deformation analysis included the following:
1. A tum on gravity analysis to evaluate the initial stresses before the input earthquake motion
was applied. At the end of the tum on gravity analysis, the calculated horizontal, vertical, and
shear stresses should satisfy the horizontal and vertical force equilibrium conditions, and
strain compatibility conditions should be satisfied as well.
2. A dynamic analysis to evaluate response and deformation of the embankment due to gravity
and the input earthquake motion. In this case, the dynamic stresses were added to the static
stresses, and the earth structure was allowed to distort (translate, rotate, compress, and
expand).
3. A post -earthquake analysis to evaluate the deformations of the embankment under gravity
loading alone following the input earthquake shaking. The input earthquake motion was
stopped, but gravity load was maintained to evaluate deformations that may have been
induced by readjustment of stresses and strains developed during earthquake shaking. The
gravity force was applied until a final, static equilibrium was achieved. Or, if the structure was
"unstable" under the post -earthquake loading, a static force imbalance would have been
maintained and the structure would continue to deform, indicating that a "flow failure" of the
impoundment would be considered a likely scenario.
Material Properties
The soil properties used in the dynamic deformation analyses were as follows:
1. Total unit weight
2. Undrained shear strength and residual shear strength
3. Initial shear modulus
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