Vertical Load Test and Settlement Analysis of Cast-in-place Concrete Nodular Piles Supporting a High-Rise Building

Abstract

 This paper describes full-scale pile load tests and 3D FEM settlement analyses regarding cast-in-place concrete nodular piles for design of a high-rise building foundation. The nodular piles have bulbs on its shaft in order to increase pile resistance.
A compressive & tensile load test and a tensile load test were carried out in the site of the high-rise building for design purpose. Each bulb of the test piles was installed in medium gravel layer and dense gravelly sand layer. Although load condition included repeated loading and long-term loading (4 days), the measured test results showed that resistance of the bulb was sufficient in both layers. Furthermore, concerning settlement behaviour of the bulb, it was attempted to normalize relationship between bearing pressure and settlement. As a result, the authors’ normalization method worked well to evaluate settlement behaviour of the bulb.

With regard to analysis, 3D FEM analyses of pile group under sustained loading and earthquake loading were conducted. These analyses were based on the analyses of the two pile load tests. In the pile group analyses, settlement of the foundation and distributions of loads on the pile head were evaluated for design. The influence of load dispersion due to stiffness of the footing beams were considerably large and marked particularly under earthquake loading.