Emirates Stadium Pile Tests

13.14.3 Static load tests for the Emirates Stadium in London

Example 13.3 looks at the design of bored piles for the Emirates Stadium in London, the new home of Arsenal Football Club.18

Seven preliminary pile tests were carried out on piles of the same diameter, but with slightly different depths of penetration. Six of the piles (P1-3 and P5-7) were of similar length, between 23.5m and 26.3m, and one pile (P4) was significantly shorter, at 16.9m. All the piles were of bored construction. Ground conditions at the pile toes were similar for all piles except two (P1 and P5), which were founded on a stiffer calcareous layer.

For design based on pile testing, it is essential that the pile tests are all carried out on similarly constructed piles in similar ground conditions. For this reason, it is arguable that not all the pile tests at the Emirates Stadium should be included in the design calculation. In this example, we have chosen to consider only those piles that are clearly comparable (i.e. P2-4 and P6-7).

The design is checked for the partial and correlation factors recommended in both Annex A to EN 1997-1 and the UK National Annex to BS EN 1997-1 (to highlight the effects of the National Annex on design).

Notes on Example 13.3

O Since the load is measured at the head of the pile, it is appropriate to ignore the weight of the pile in the analysis.

© In order to apply the correlation factors given in EN 1997-1, it is essential that the pile tests should be considered to be representative of the same data set. Therefore those tests that cannot be treated as being essentially of similar design, construction, and founded in similar materials should be excluded. It could be debated whether the two piles of similar length to the others but with significantly lower settlement do or do not form part of the same data set. It is highly unlikely that one could ever get a sufficiently large data set of similar tests to take advantage of this approach and yet this is Eurocode 7's preferred method.

© The factor of 1.1 is specified in §7.6.2.2 of EN 1997-1.

© Adopting the EN 1997-1 values for partial factors results in a design that meets the requirements of the code.

Example 13.3

Static load tests for the Emirates Stadium load tests in London Verification of strength (limit state GEO)

Design situation

Consider the design of piles for the Emirates Stadium in London (the new home of Arsenal Football Club) where a large number of bored piles of different diameters are to be installed. Ground conditions at the site comprise 2.9m Made Ground, 2.1m Terrace Gravels, 31.0m London Clay, and at least 5m Lambeth Clay. Assume the top L0 = 5m of the ground profile provides negligible skin friction to the piles.

Load tests have been perfomed on seven piles, all with the same diameter Dm = 600mm but with different total lengths L^ (Pile test data courtesy

Stent Foundations Ltd.) The peak applied load P and the corresponding settlement at that load is given below for each pile:

Stent Foundations Ltd.) The peak applied load P and the corresponding settlement at that load is given below for each pile:

25.4m ^

0 0

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