UNDERSTANDING THE TRENDS OF LOAD-SETTLEMENT CURVES OF RAPID LOAD TESTS

The Rapid Load Testing (RLT) of foundation piles has been applied worldwide since 1984. Several international and national codes are available. For checking the performance of piles, they are more economical, faster and environmentally friendly than Static Load Testing (SLT), while yielding good correlations with SLT results through an objective analysis method. In Singapore, most of the foundation piles in Singapore are usually socketed into competent soil material (SPT N>100) or hard rock. In addition to the usual pile bearing capacity with adequate factor of safety, local regulation stipulates that the pile has to satisfy the serviceability criteria, which is pile top settlement less than 15 mm for 1.5 times working load, or less than 25 mm for 2 times working load. To date (January 2022), over one thousand RLT (by StatRapid Load Test method) have been successfully tested in Singapore. It was observed that the loadsettlement pattern of the multiple cycles of StatRapid test actually gives useful indication of the performance of the pile – from very elastic behavior to near geotechnical failure case. If the pile is undergoing structure failure (i.e. material yielded or cracked) during the loading stage, the multiple cycle load-settlement result will also show unique patterns. Hence, the StatRapid load-settlement results can also be used to “indicate” the health of the pile. This paper aims to introduce five unique patterns of the StatRapid multiple cycle load-settlement responses, with correlation to their actual pile performance. Actual case studies representing several common scenarios will be presented and discussed