Effects of Pile Size on Set-Up Behavior of Cohesive Soils

Abstract

Driven piles usually experience significant increase in axial load resistance over time, known as set-up. A large portion of this set-up can be completed within the first few hours, and can also take a few days to months for set-up to complete. Dynamic and static load tests are usually performed to verify the axial resistances of piles at specific times after end of driving (EOD) and to quantify these resistances. The pile driving and testing records of 45 square precast prestressed piles (PPC) of various sizes from several projects conducted by the Louisiana Department of Transportation and Development (LADOTD) were collected in a database. These records include dynamic testing at end of driving and restrikes at various times after driving, in addition to static load tests. Four different size groups (14 in., 16 in., 24 in., and 30 in.) are used to study the size effect on pile set-up. This study is aimed at evaluating the effect of pile size on set-up phenomenon under similar soil condition. Results of the analyses show that the set-up ratio increases with increasing pile sizes after a given setup time. The pile testing database is also used to calculate the set-up rate of different pile sizes using the Skov and Denver (1988) methodology. Interestingly, the set-up rates observed from the load test database as reflected by the Skov and Denver's "A" parameter are also size dependent. The results indicate that pile set-up increases with increasing pile sizes.

پیش‌بینی ظرفیت باربری وابسته به زمان شمع‌های کوبشی در خاک چسبنده با استفاده از روش گروهی مدیریت داده‌ها

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Developing a Model to Estimate Pile Setup for Individual Soil Layers on the Basis of Piezocone Penetration Test Data

“…The parameter A can be assumed, backcalculated from field data, or gleaned from empirical relationships available in the literature. Published literature has shown that the parameter A is a function of soil type and properties, and pile type and size (1,3,10,11). A few studies have described the effects of soil properties on the magnitude or rate of setup and incorporated soil properties in the setup prediction model.…”