Analysis of Drilled, Cast In-Situ Single Piles in Axial Loading
Research Fellow, Faculty of Technology, University of Glamorgan, Pontypridd, CF37 1DL, United Kingdom
Professor, Faculty of Technology, University of Glamorgan, Pontypridd, CF37 1DL, United Kingdom
A semi-analytical method is developed for predicting the load-settlement behavior of vertically loaded piles formed in weak rocks and cohesive soils. The aim is to have a simpler and more cost-effective alternative to the traditional load transfer (t-z) method, whereby the data required from various depths, are not only difficult to interpret from routine site investigations but also costly to develop from sophisticated field tests. The proposed method is based on formulating generic functions to uncouple shaft and base transfer mechanisms. The functions are developed through analysis of field performance data from instrumented pile tests. After combining the generic functions with the basic governing equations for soil-pile interaction, the full set of equations is solved iteratively with the aid of a newly developed computer program. The program computes the ratio of load sharing between the shaft and the base, at every stage of loading, leading to determination of the axial force distribution and load-settlement variation. Using the program, load-settlement predictions are carried out for 3 CFA piles formed in mudstone. Also, parallel predictions are made using the t-z approach and another published method. In every case, it is shown that the proposed method yields the most accurate predictions.
Keywords: piles, settlement, cohesive soils, weak rocks.
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