Rapid Load Testing in GermanyÂ-Paper

Paper
Pdf Summary
The paper presents Rapid Load Testing (RLT) as a practical alternative to static load testing (SLT) and high-strain dynamic testing (DLT). RLT applies a relatively long force pulse, using either a launched reaction mass (Statnamic) or a cushioned falling weight (StatRapid), so the pile and surrounding soil behave approximately as a single system. This quasi-static response mobilizes shaft and toe resistance together and avoids the stress-wave effects central to DLT.<br /><br />RLT measures load and displacement directly, producing a load–settlement curve without relying on assumed pile properties or subjective signal matching. The authors recommend the Unloading Point Method (UPM) to estimate equivalent static resistance. RLT is quick, requires little site space, avoids counterweights and temporary anchors, and causes no damaging impact stresses. It can be used for working piles, design verification, and troubleshooting; additional instrumentation can provide shaft-friction and toe-resistance data.<br /><br />A case study in Rostock, Germany, tested six approximately 18 m long, 620 mm diameter bored piles. A StatRapid device completed the campaign in two days, compared with an estimated two weeks or more for SLT. Test loads corresponded to 4.0–5.3 MN. The results produced load–settlement behavior considered reliable and consistent with the method’s established correlations with SLT.<br /><br />The main qualification is loading-rate effects, especially near ultimate capacity and in fine sand or clay. Appropriate reduction factors should be applied; the study used 0.94 for predominantly sandy ground. Overall, the authors conclude that RLT can replace SLT for assessing pile load–settlement performance when interpreted with UPM and suitable rate corrections.
Keywords
Rapid Load Testing
RLT
Static Load Testing
SLT
Dynamic Load Testing
DLT
Statnamic
StatRapid
Unloading Point Method
Pile Load Settlement