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Showing 3 results for Deep Foundation

F. Messaoud, M. S. Nouaouria,
Volume 8, Issue 1 (3-2010)

This paper presents a description of the equipment, testing procedure, and methodology to obtain ground

mechanical parameters. The p-y curves for laterally loaded piles are developed. Methods for the development of p-y

curves from pressure meter and dilatometer (DMT) test are described. P-y curves are used in the analysis to represent

lateral soil-pile interaction. The pressure meter offers an almost ideal in-situ modeling tool for determining directly

the p-y curves for the design of deep foundations. As the pressure meter can be driven into the soil, the results can be

used to model a displacement pile. DMT tests were performed for comparisons with PPMT tests. Correlations were

developed between the PPMT and DMT results, indicating a consistency in soil parameters values. Comparisons

between PPMT and DMT p-y curves were developed based on the ultimate soil resistance, the slope of the initial

portion of the curves, and the shape of the curves. The initial slope shows a good agreement between PPMT and DMT

results. The predicted DMT and PPMT ultimate loads are not similar, while the predicted PPMT and DMT deflections

within the elastic range are identical.

A. Eslami, I. Tajvidi, M. Karimpour-Fard,
Volume 12, Issue 1 (1-2014)

Three common approaches to determine the axial pile capacity based on static analysis and in-situ tests are presented, compared and evaluated. The Unified Pile Design (UPD), American Petroleum Institute (API) and a SPT based methods were chosen to be validated. The API is a common method to estimate the axial bearing capacity of piles in marine environments, where as the others are currently used by geotechnical engineers. Seventy pile load test records performed in the northern bank of Persian Gulf with SPT profile have been compiled for methods evaluation. In all cases, pile capacities were measured using full scale static compression and/or pull out loading tests. As the loading tests in some cases were in the format of proof test without reaching the plunging or ultimate bearing capacity, for interpretation the results, offset limit load criteria was employed. Three statistical and probability based approaches in the form of a systematic ranking, called Rank Index, RI, were utilized to evaluate the performance of predictive methods. Wasted Capacity Index (WCI) concept was also applied to validate the efficiency of current methods. The evaluations revealed that among these three predictive methods, the UPD is more accurate and cost effective than the others.
M. Zare, A. Eslami,
Volume 12, Issue 4 (12-2014)

Physical modeling for study of deep foundations can be performed in simple chambers (1g), calibration chambers (CC),

and centrifuge apparatus (ng). These common apparatus face certain limitations and difficulties. Recently, Frustum Confining

Vessels (FCV) have been evolved for physical modeling of deep foundations and penetrometers. Shaped as the frustum of a

cone, this device applies steady pressure on its bottom and creates a linear stress distribution along its vertical central core.

This paper presents the key findings in FCV, as developed in AUT. The FCV has a height of 1200 mm, with top and bottom

diameters of 300 and 1300 mm, respectively. By applying bottom pressure up to 600 kPa, the in-situ overburden stress

conditions, equivalent up to 40 m soil deposits, become consistent with the embedment depth of commonly used piles.

Observations indicated that a linear trend of stress distribution exists, and this device can create overburden stress in the

desired control volume along the central core. Moreover, a couple of compressive and tensile load tests were performed on

steel model piles driven in sand with a length of 750 mm, and different length to diameter (L/D) ratios between 8-15.

Comparison between measured and predicted ultimate capacity of model piles performed in FCV demonstrate a suitable

conformity for similar confinement conditions in the field. Therefore, the FCV can be considered as an appropriate approach

for the investigation of piling geotechnical behavior, and the examination of construction effects.

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