Design Versus Load Testing: A Case Study on 124 Load Tests

In Belgium, geotechnical pile design is governed by ultimate capacity, and rarely involves the behaviour at service loads. On the other hand, a typical load test campaign focusses on the service settlement, and rarely reaches the ultimate capacity. This paper presents a case study for which this contrast between design and testing gave rise to a discrepancy in the measured settlements. A total of 5 static load tests and 124 dynamic load tests were performed on screw displacement, continuous flight auger (CFA), and bored piles. The measured settlement at service working loads ranged from 1 to 10 mm, despite a repetitive design made in relatively homogeneous ground conditions. Although all the piles satisfied the client settlement criteria, some piles did overperform. Therefore, there is room to improve the design in order to reduce, amongst other things, the environmental impact of the foundations.