Medium dense gravelly SAND grSa

Figure 13.18. Concrete pile driven into clay and sand

The design in this example compares the three Design Approaches discussed in Chapter 6, using the partial factors specified in Annex A of EN 1997-1. Eurocode 7 emphasises design of piles via testing and gives little guidance to design by calculation. This example uses standard UK calculation procedures and highlights some areas where there is debate how Eurocode 7 should be applied.

Notes on Example 13.1

O Unlike other geotechnical structures, for DA1 the partial factors applied to material properties are always 1.0 and therefore characteristic material properties are used to derive characteristic shaft resistance and end bearing.

Example 13.1 Concrete pile driven into clay and sand Verification of strength (limit state GEO)

Design situation

Consider a square concrete pile of breadth b = 400mm, which is driven to a depth L = 10.0m into a medium strength sandy CLAY overlying medium dense gravelly SAND, and carries imposed loads = 650kN (permanent) and

VQk = 250kN (variable). The weight density of reinforced concrete is kN

Yck = 25-(as per EN 1991-1-1 Table A.1). The clay, which is t1 = 8m m thick, has characteristic undrained strength cuk = 45kPa and weight density kN

Yk = 18.5-. The sand has drained strength parameters f>k = 36° and m kN

c'k = 0kPa and weight density Yk = 20-. The sand's constant-volume

2 m angle of shearing resistance is ^>cv k = 33°. Groundwater has been found at a depth dw = 1m and skin friction on the pile will be ignored above that depth (to allow for whipping during installation, etc.).

Design Approach 1

Actions and effects

Characteristic self-weight of pile is Wgk = Yck x b x L = 40 kN
0 0

Post a comment