Author : Nontapat Nimityongskul
Release : 2011
Genre : Lateral loads
Kind : eBook
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Book Synopsis Effects of Soil Slope on Lateral Capacity of Piles in Cohesive Soils by : Nontapat Nimityongskul

Download or read book Effects of Soil Slope on Lateral Capacity of Piles in Cohesive Soils written by Nontapat Nimityongskul. This book was released on 2011. Available in PDF, EPUB and Kindle. Book excerpt: Pile supported bridges are typically constructed near or in a natural or man-made slope and are subjected to lateral loading. The current design method for laterally loaded piles involves the use of Winkler's spring concept with the standard nonlinear p-y curves. The available p-y curves were developed based on results of full-scale lateral loading tests for piles in level ground. Due to limited test results from full-scale lateral loading tests for piles installed near a slope, current practice has no specific procedures for the design of piles in such condition. This study is aimed at obtaining a better understanding of the effects of slope on lateral capacity of piles through experimental and analytical programs. A series of full-scale lateral loading tests on instrumented piles in cohesive soils were conducted at Oregon State University in 2009 to assess the behavior of laterally loaded piles in free-field and near slope conditions. Data from the tests was used to backcalculate p-y curves. It was found that for small soil displacements (i.e., less than 0.5 inch), the proximity of slope has small to insignificant effect on the lateral pile response. At larger soil displacements, the proximity of slope adversely affected the lateral capacity of the soil-pile system and consequently the p-y curves. Specifically with regard to Caltrans Bridge Design Specifications Article 4.5.6.5.1, for maximum allowable pile deflection of 1/4-inch under Service Limit State Load, the soil slope appears to have insignificant effects for piles installed at 2D or further from the slope crest, where D is the pile diameter. For piles installed on the slope crest (0D), the effects of slope are most pronounced and should be considered at all displacement levels. The effects of slope on the lateral capacity were insignificant for piles installed at distances of 8D or greater from the slope crest. Based on comparisons of the back-calculated p-y curves from these experiments, p-multipliers are proposed as a function of soil displacement to account for slope effects. Using the full-scale test results, the capability of available p-y curves to predict the lateral response of free-field piles was evaluated. It was found that standard p-y curves available in the literature for cohesive soils give reasonable predictions of the lateral pile response for free-field piles. Hyperbolic p-y criteria appear to be most suitable to describe the back-calculated baseline p-y curves from this study. In addition, the capability of existing p-y recommendation for piles on a slope crest was evaluated; design guidelines based on the findings from this study is presented. Finally, the finite element program Plaxis 3D was used to simulate the lateral loading tests. The procedure was validated by comparing the computed results with the full-scale test results.