Eurocodes: Background & Applications GEOTEC GEO TECHNI HNICAL CAL DESIGN DESIGN wi th wor ked ex amples
13-14 1314 Jun e 2013, 2013, Dubli n
– T-shaped gravity wall Dr Andrew Bond Director, Geocentrix Ltd Chairman TC250/SC7
Eurocodes: Background & Applications GEOTECHNICAL DESIGN wi th wor ked ex amples
Worked example – T-sha ed ravit wall
DESIGN SITUATION
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Eurocodes: Background & Applications w
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Design situation for gravity wall example
3
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Eurocodes: Background & Applications w
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Earth pressure theory Use Rankine’s equation for Ka:
K a , β
cos β
−
=⎜ ⎜ cos +
cos
2
β − cos2ϕ
cos
2
− cos
2
⎟ cos β ⎟
Horizontal and vertical component of K a are:
4
K a ,h
= Ka , β × cosβ
K a ,v
= K a , β × sin
= K a ,h × tan β
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Some numbers to save you time... Self-weight of wall stem
Wstem ,k
= γ c ,k × t s × H = 25 × 0.7 × 6 = 105
Self-weight of wall base
Wbase ,k
N m
= γ c ,k × t b × B = 25 × 0.8 × 3.9 = 78 kN
Self-weight of backfill
Wfill ,k
= γ k × bheel × ⎜ ⎝ = 19 × 2.25 × ⎜ ⎝
5
+
f
2
⎟ ⎠
6 + 6.82
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2
m
⎟ = 274 kN ⎠
m
Eurocodes: Background & Applications w
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Bearing capacity coefficients Nq
Nq
.
.
21
7.1
31
20.6
22
7.8
32
23.2
23
8.7
33
26.1
24
9.6
34
29.4
25
10.7
35
33.3
26
11.9
36
37.8
.
6
.
28
14.7
38
48.9
29
16.4
39
56.0
©2005-13 Geocentrix Ltd. All rights reserved
Eurocodes: Background & Applications w
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Worksheet – T-shaped gravity wall Calculate: 2. Moments about wall toe, the determine eccentricity of 3. Bearing resistance under eccentric, inclined loads . 5. Toppling resistance
7
©2005-13 Geocentrix Ltd. All rights reserved
Eurocodes: Background & Applications GEOTECHNICAL DESIGN wi th wor ked ex amples
Worked example – T-sha ed ravit wall
SOLUTION
13-14 Jun e 2013, Dubli n
Eurocodes: Background & Applications w
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une,
u
n
Solutions DA1/DA2* – T-shaped gravity wall Verification
DA1
DA2*
Traditional
-
-
Sliding
66%
85%
99%
Fs = 1.52
Bearing
125%
230%
93%
Fb = 2.03
Eccentricity
0.92 m
0.64 m
0.42 m
Effective width
2.05 m
2.63 m
3.06 m
Same as DA2*
31%
31%
31%
FO = 4.35
Toppling
9
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Eurocodes: Background & Applications w
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Summary of key points DA2* requires a wall base of width B ≥ 3.9 m = = DA1 requires a wall base of width B ≥ 5.1 m qu va en o ra ona s = . an . b = Main difference between DAs 1 and 2* is bearing resistance Calculated load eccentricity is very different Effective width is much smaller in DA1
10
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Eurocodes: Background & Applications GEOTECHNICAL DESIGN wi th wor ked ex amples
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Eurocodes: Background & Applications GEOTECHNICAL DESIGN wi th wor ked ex amples
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