EARTHQUAKE SAFETY EVALUATION OF ATATURK DAM
EARTHQUAKE SAFETY EVALUATION OF ATATURK DAM
EARTHQUAKE SAFETY EVALUATION OF ATATURK DAM
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given. For this purpose, the sliding movement was assumed to occur in the direction of the tangent at<br />
the highest point of the sliding surface.<br />
Table 3: Permanent displacements of critical sliding block on upstream slope<br />
(Notation: ayield: yield acceleration; dh: horizontal displacement; dv: vertical displacement)<br />
Peak angles of friction Residual angles of friction<br />
Considering only<br />
Considering only Considering horizontal and<br />
horizontal acceleration horizontal acceleration vertical accelerations<br />
ayield<br />
(g)<br />
Max./<br />
Mean/<br />
Min.<br />
dh<br />
(m)<br />
dv<br />
(m)<br />
ayield<br />
(g)<br />
Max./<br />
Mean/<br />
Min.<br />
(a) With average dynamic material properties<br />
dh<br />
(m)<br />
dv<br />
(m)<br />
ayield<br />
(g)<br />
Max./<br />
Mean/<br />
Min.<br />
Max. 0.41 0.26 Max. 1.03 0.64 Max. 2.34 1.46<br />
0.239 Mean 0.32 0.20 0.185 Mean 0.91 0.57 0.139 Mean 2.03 1.27<br />
Min. 0.19 0.12 Min. 0.79 0.50 Min. 1.66 1.04<br />
(b) Considering possible upper and lower bounds of dynamic material properties<br />
Max. 1.28 0.80 Max. 2.28 1.42 Max. 3.72 2.32<br />
0.239 Mean 0.47 0.29 0.185 Mean 1.07 0.67 0.139 Mean 2.17 1.36<br />
Min. 0.03 0.02 Min. 0.18 0.11 Min. 0.98 0.61<br />
dh<br />
(m)<br />
CONSEQUENCES <strong>OF</strong> <strong>EARTHQUAKE</strong>-INDUCED SLIDING DISPLACEMENTS<br />
The most important consequences of the sliding movements induced by the earthquake loading are<br />
discussed below.<br />
Reduction of available freeboard<br />
During a major earthquake, the crest region can be expected to undergo sliding movements towards<br />
both the upstream and downstream sides along a number of criss-crossing failure surfaces. The sliding<br />
movements are likely to be of intermittent nature. Consequently, the displacements towards the<br />
upstream and downstream sides would occur at different times and, thus, can be assumed to have a<br />
cumulative effect on the vertical displacement of the crest region. Hence, the total drop of the level of<br />
the core top was assumed to be equal to the sum of the vertical displacements occurring during the<br />
sliding displacements towards the upstream and downstream sides.<br />
Based on the results for the average properties, the total vertical drop of the core top would be about<br />
1.0 m during the MCE due to the downward vertical displacements of 0.8 m and 0.2 m produced by<br />
sliding towards the upstream and downstream sides, respectively. However, if the dynamic shear<br />
moduli approach the upper bound values (case E), the total lowering of the level of the core top could<br />
become as high as 2.3 m as a result of vertical displacements of about 1.5 m and 0.8 m during the<br />
sliding movements caused by the MCE towards the upstream and downstream sides, respectively.<br />
Besides the permanent sliding displacements resulting from the dynamic slope instabilities, the<br />
earthquake ground shaking also produces a general settlement due to the vibration-induced<br />
densification of the embankment materials. The maximum seismic settlement of the top of the core<br />
due to this effect was estimated to be of the order of 0.5 m.<br />
Considering the effects of both the movements of potential sliding masses and the general seismic<br />
settlement, it was estimated that the lowering of the elevation of the core top could approach the order<br />
of 3 m during the MCE. Therefore, the freeboard with respect to the core top must be sufficient at all<br />
times to accommodate such a reduction without endangering the safety of the dam.<br />
dv<br />
(m)