Design of Embankment Dam and Stability Analysis of Existing Slopes

The assignment content involves the design of an embankment dam for a reservoir. The task includes calculating various values such as uplift pressure, water rate, and stability analysis of existing slopes. The provided spreadsheet contains data from borehole measurements to determine the critical failure surfaces and factor of safety (FOS) for the existing slopes. The first critical slope is 1.7:1, and an SLOPE/W analysis will be performed to analyze this slope.

Task4. Embankment Dams
Solution: Estimated daily seepage rates has been calculated for every node in the dam with the SEEP/W
analysis.
SEEP/W: For embankment
Node
Water Rate
(m³/d)
43 0.016984711
44 7.32E-16
53 -2.78E-15
54 0.021097643
62 6.44E-15
64 9.51E-16
65 0.025834769
66 -5.85E-16
75 -2.93E-16
76 -2.93E-15
77 0.031974502
78 -9.66E-15
79 8.78E-15
88 9.15E-15
89 0.038630038
90 3.95E-15
91 -7.61E-15
100 1.83E-15
101 0.046110507
102 -7.32E-16
111 5.56E-15
112 -2.05E-14
113 6.15E-15
114 0.055136
115 4.54E-15
116 -3.81E-15
122 0.064733867
126 5.12E-15
127 2.93E-16
128 -3.22E-15
129 0.07562984
130 -8.78E-15
131 -6.44E-15
140 -3.81E-15
141 9.95E-15

142 2.49E-15
143 0.087705816
152 1.84E-14
153 2.34E-15
154 -6.44E-15
155 -1.17E-15
156 -1.17E-15
157 0.10156377
158 -1.14E-14
167 -4.10E-15
168 0
169 2.05E-15
170 2.63E-15
171 -3.66E-15
For Underlining soil:
Node
Water Rate
(m³/d)
160 4.39E-15
161 5.96E-15
162 -5.31E-15
163 -4.43E-15
164 3.40E-15
165 2.49E-15
166 -3.22E-15
176 -1.46E-16
177 1.06E-15
178 -2.52E-15
179 6.22E-16
180 -2.41E-15
181 -4.10E-15
182 6.44E-15
193 1.87E-15
194 -4.61E-15
195 5.67E-15
197 1.57E-15
198 5.85E-15
199 -5.42E-15
200 -6.44E-15
210 1.54E-15
211 -7.32E-17
212 -2.31E-15

SEEP/W with Drain: For dams
Node
Water Rate
(m³/d)
22 0.01418434
32 0.017612237
33 1.61E-15
43 0.021426687
44 2.63E-15
54 0.02660308
62 7.03E-15
65 0.032562859
66 -1.17E-15
76 -4.10E-15
77 0.04028322
78 -9.37E-15
79 6.73E-15
89 0.048646986
90 -1.20E-14
91 5.85E-16
101 0.058043459
102 2.78E-15
112 -1.87E-14
113 9.66E-15
114 0.069372528
115 -7.61E-15
116 3.51E-15
122 0.081409884
127 -5.56E-15
128 1.32E-14
129 0.095062562
130 -5.27E-15
131 -8.20E-15
141 9.07E-15
142 -6.15E-15
143 0.11017652
153 6.44E-15
154 1.46E-16
155 4.10E-15
156 3.37E-15
157 0.12749352

158 -1.05E-14
168 3.51E-15
169 1.46E-15
170 -4.10E-15
171 1.76E-15
172 0.14680481
173 -4.68E-15
174 1.46E-15
184 -4.68E-15
185 -8.20E-15
186 -3.22E-15
187 8.78E-15
For Underlining Soil:
Node
Water Rate
(m³/d)
261 -5.49E-15
262 -7.68E-15
263 6.11E-15
264 -1.28E-15
265 -7.32E-17
266 -2.85E-15
267 -6.29E-15
281 2.93E-16
283 -2.63E-15
284 3.00E-15
285 -5.12E-15
286 4.02E-16
287 -5.12E-16
288 -9.51E-16
301 1.90E-15
302 3.29E-16
303 5.42E-15
304 -1.76E-15
305 2.12E-15
A sketch of the cross-section per dams recommend for construction
The recommended dam is embankment dam with toe drain.

Uplift Pressure
For embankment dam design without toe drain
PWP through embanment
0 sec
W a t e r T o t a l H e a d ( m )
X (m)
15.46
15.48
15.5
15.52
15.54
15.56
15.58
15.6
15.62
15.64
15.66
For embankment dam design with toe drain

PWP through embanment
0 sec
Water Total Head (m)
X (m)
14.7
14.75
14.8
14.85
14.9
14.95
15
15.05
33.995 34 34.005 34.01 34.015 34.02 34.025 34.03 34.035 34.04 34.045 34.05
Task 5. Stability of Existing Slopes
First of all, we have to find the two most critical existing slope of the reservoir for sliding. A spreadsheet
is given below:

Bore
Hole
Distance
between
boreholes
Ground
Surface
level
Diff.
b/w
GS
level
Horizontal
Distance b/w
Boreholes
Existing
Slope(H:V) Remarks
BH1 224.00
37 3.75 36.81 9.8 9.8:1
BH2 220.25
24 8.75 22.35 2.6 2.6:1
BH3 211.50
19 6.75 17.76 2.6 2.6:1
BH4 204.75
24 3.75 23.71 6.3 6.3:1
BH5 201.00
16 8.00 13.86 1.7 1.7:1 Critical
BH6 209.00
13 8.75 9.61 1.1 1.1:1 Critical
BH7 217.75
25 3.25 24.79 7.6 7.6:1
BH8 221.00
First critical slope is 1.7:1. Let us taken first and will be done with SLOPE/W analysis.
Critical Failure Surface is shown in figure below:

FOS=1.544