Strainstall (United Kingdom)

Abstract Static load tests are vital to assess the genuine behaviour of piles to substantiate the geotechnical design parameters and construction approaches. A load testing program was undertaken to determine the working capacity, skin friction, and settlement of drilled shafts in Simsima limestone, the predominant foundation stratum in Doha, Qatar. The weathering profile of the Simsima limestone is complex with the degree of weathering likely to increase with depth. This paper presents the performance of three preliminary instrumented bored cast-in-situ test piles (Type 1, Type 2 and Type 3) by Bi-directional static load test (BDSLT) using sacrificial hydraulic jacks, socketed in the weathering zones of Simsima limestone formation in Lusail FIFA World Cup 2022 stadium project, Qatar. The test piles were instrumented with vibrating wire strain gauge technology and were load tested using the BDSLT loading method to determine the pile-rock interactions within the various weathering zones of Simsima limestone. The unit shaft friction values obtained from the load test are compared with the initial design values. Results indicate that the skin friction was increased from values reported before pile load testing and was used for the optimization of pile design. BDSLT method with strain gauge instrumentation is a modern tool in value engineering of pile design to provide accurate information to the Qatar infrastructure foundation industry.

Abstract The application of a static load test in the optimisation and verification of pile design is mandatory in any foundation industry. Bi-Directional Static Load Test (BDSLT) is carried out using a hydraulically driven, purpose built, calibrated, sacrificial loading cell installed within the foundation unit. As the load is applied to the cell, it begins working in two directions; upward against upper side shear and downward against base resistance and lower side shear. Bidirectional Static Load Test (BDSLT) is a modern full-scale proofing load test method in the realm of performance-based pile design. Due to the many advantages over the conventional top-down load test, the Bidirectional Static Loading Test (BDSLT) using the hydraulic jacks is becoming an increasingly popular way to determine the ultimate capacity of deep foundations. Bidirectional loading tests are now becoming common practice around the Middle East and other countries, more convenient than traditional top-down loading tests. Strainstall has pioneered a practice of bidirectional test in conjunction with strain gauge instrumentation, which has vastly contributed to the knowledge and state of the art of pile response to load. This test is widely used in both preliminary and working compression and tension tests. BDSLT was carried out for a 2000 mm diameter pile in Dubai to a test load of 15,700 KN along with twenty levels of strain gauges to understand the geotechnical behaviour of the pile, also discuss the influence of different parameters on strain gauge reading and its possible solutions.KeywordsBidirectionalFoundationPileStrain gauge