Search

This paper presents the results from a prediction event, organized by the University of Western Australia (UWA) and the National Geotechnical Centrifuge Facility (NGCF), and performed as part of the International Symposium on Frontiers in Offshore Geotechnics to assess uncertainty in predicting the monotonic and cyclic lateral response of conductors. Geotechnical professionals from around the world were invited to predict the response of a model conductor (a flexible pile) subjected to a series of loading sequences in a centrifuge. A normally consolidated fine-grained soil was used in the tests, which was characterized by soil elements and in-flight T-bar penetrometer testing. While some participants provided accurate predictions, the mean response was an overestimate of the monotonic and cyclic load at the pile head, which was significant for large and very small displacements. An analysis of the submissions is presented to quantify the variability of the predictions received, assess the consequences of each design, and relay the uncertainty associated with engineering judgment in design. [ABSTRACT FROM AUTHOR]

For this set of tests, the strain rate of the T-bar and centrifuge tests (calculated as the displacement normalized by the T-bar/pile diameter and divided by the time) were broadly comparable, as can be observed from Fig. Undrained shear strength against strain rate of simple shear, T-bar, and centrifuge tests. As noted in the original paper, the T-bar undrained shear strength gradient yielded a very similar value as the strength gradient calculated from the simple shear tests at a slow rate, despite the T-bars being performed at (considerably) higher strain rate than the slow simple shear tests. [Extracted from the article]

Solutions are presented for stiffness coefficients to represent the elastic behavior of a caisson foundation embedded in soil. The solutions use a novel numerical technique, the scaled boundary finite element method, combined with shell elements to represent the foundation itself. The stiffness coefficients take into account the possibility of nonhomogeneity in the soil (stiffness varying with depth), the geometry of the foundation, and the contribution to the stiffness of the skirt of the caisson foundation. Tabulated values allow a simple curve fit to the stiffness values to be employed for particular cases. The accuracy of the method is tested against previous solutions for particular cases. Example calculations are given to illustrate the method. [ABSTRACT FROM AUTHOR]