Publication Abstract

Proceedings - Fifth International Conference & Exhibition on Piling and Deep Foundations, 1994, Bruges, Belgium, (DFI)

Use of high capacity piles in bridge foundations with full scale test results
J.A. Mason

Analysis of existing viaducts in the San Francisco Bay Area directly after the 1989 Loma Prieta earthquake showed that numerous foundations were inadequate for large seismic demands. Since then, Caltrans has invested a portion of its resources to this problem. This paper will briefly explore the problem of inadequate foundation moment and shear capacities of existing footings. Also, two recent FULL SCALE PILE TEST RESULTS are presented. Both tests were conducted in San Francisco, California, with the predominant soil type being SOFT BAY MUD. First, the "Pile Load Test", was conducted to investigate the adhesion capacity of axially loaded piles that were founded through deep soft Bay Mude. This full scale test was conducted in 1992 to get some "real numbers" for the tension and compression capacities of standard plan piles and of high capacity proprietary piles. A total of 81 compression and/or tension tests were conducted. All piles were loaded until they reached GEOTECHNICAL FAILURE, i.e. a slip state. The second test was of two full scale PILE GROUPS IN LATERAL LOADING. This report presents some of the original test results. It should be noted that each pile group was pushed to a slip state through the soil mass. From this, preliminary conclusions can be drawn about the degradation of the goup stiffness at large strains. Analysis of one pile group capacity was conducted to investigate codified group reduction factors.

 article #785; publication #36 (IC-1994)