Pile Design and Construction Practice, Fifth edition

324 Piles to resist uplift and lateral loading
(a)
Vc/L 3
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
In addition to dealing with the use of anchorages for restraining uplift on structures, EC7
(Section 8) makes recommendations covering anchorages for retaining walls, slopes, cuttings
and tunnels. Only their applications relevant to uplift on structures will be described below.
EC7 requires tension piles, where used as anchors, to be designed as described for compression
piles in Section 7 of the Code. In the case of anchorages formed by grouting tendons into
drilled holes, EC7 requires their design and installation to be in accordance with BS EN
1537: 1999, Ground anchors, which could eventually supersede the more comprehensive
BS 8081 referred to above.
BS EN 1537 defines temporary anchors as those with a design life of less than two years,
and permanent anchors as those with a design life of two years or more. The ultimate limitstates
to be considered are the same as those listed at the beginning of this section. In addition,
BS EC7 and EN 1537 require design measures against the following:
(1) Structural failure of the anchor head
(2) Distortion or corrosion of the anchor head
n/L
u
30°
30°
m/L
Anchor
Vc/L 3
n
L
Volume of cone
V c
Overlap
volume DV
3.2
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0
30 40 50 60 70 80 90
(Vertical)
Angle of inclination θ of anchor to
horizontal in degrees
Figure 6.17 (a) Chart for calculating volumes of single or over-lapping cones with vertical or inclined axes.
m
0.4
0.2
0
m/L and n/L