Ultimate lateral capacity of piles in clay
This paper presents the results of centrifuge tests and analyses performed to determine the influence of cyclic lateral loading on the ultimate lateral resistance of foundation piles in normally consolidated clay soil. The work was motivated by the need for an appropriate method for estimating lateral soil resistance in order to assess the foundation reserve strength ratio (RSR) of fixed offshore platforms. In the absence of test data, industry practice has been to use the fully degraded cyclic resistance from the working stress design criteria recommended in API RP2A for cyclically loaded piles. It was suspected that this working stress approach substantially underestimates the ultimate lateral soil resistance available. The data reported herein demonstrate that while the cyclic criteria are appropriate for working stress analyses, they are extremely conservative for ultimate strength analyses. It is recommended that the non-degraded, static clay criteria be used to obtain soil resistances for use in RSR calculations. Since the data were obtained in kaolin, caution should be used when dealing with highly sensitive or fissured soils; in those cases additional study may be warranted. The data reported herein show that when the pile displaces into undisturbed soil, the ultimate resistance that can be mobilized is, to a large extent, regained. The most significant implication of this finding is for platforms whose foundation reserve strength is controlled by lateral pile resistance. Platforms most favorably affected by the conclusions of this study are older, shallow water template-type jackets with unbattered piles. Using the criteria recommended herein, the computed foundation RSR of such platforms is raised about 30 percent over that computed using cyclic criteria.
- OSTI ID:
- 136631
- Report Number(s):
- CONF-950501-; TRN: IM9552%%173
- Resource Relation:
- Conference: 27. offshore technology conference, Houston, TX (United States), 1-4 May 1995; Other Information: PBD: 1995; Related Information: Is Part Of 27. Annual Offshore Technology Conference: 1995 Proceedings. Volume 1: Geology, earth sciences and environmental factors; PB: 541 p.
- Country of Publication:
- United States
- Language:
- English
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