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An experimental investigation on the coefficient of earth pressure of overconsolidated cohesionless soil developed around displacement piles was conducted. An instrumented prototype set-up and model pile was developed in the laboratory. The set-up was capable of measuring the total load, the shaft resistance acting on the pile and the overconsolidation ratio in the sand mass. Overconsolidated sand was prepared by placing the sand in the testing tank in layers, each subjected to a predetermined compaction effort. The stresses in the sand mass were measured by means of pressure transducer units placed in selected locations in the testing tank. The model piles were driven into the sand mass to a selected depth. Pile load tests were conducted at a constant rate of penetration at different depths. The pile capacity was determined from load-displacement curves. The shaft resistance and, hence, the coefficient of earth pressure around the pile were determined. The results showed that the coefficient of earth pressure is heavily dependent on the stress history of the sand mass. A theoretical model was developed to incorporate the effects of overconsolidation of the sand on the shaft resistance of driven piles in cohesionless soils.
The present work contains 150 papers that were presented during ISEC-03, the 3rd International Conference on Structural and Construction Engineering, that was held in Tokuyama College of Technology, Shunan, Japan, from September 20 to 23, 2005. The theme of the conference was Collaboration and Harmony of Creative Systems. The conference was to encourage and assist the collaboration of any and all kinds of structural, system, and construction engineering using information technology in an environmentally friendly manner. This book contains these challenging papers.
Pile foundations are used extensively around the world to support both inland and offshore structures, including important structures such as nuclear plants and oil drilling platforms. Pile foundations are known to resist higher compression and uplift loading as compared to shallow foundations. The common factor in resisting the compression and the tensile loading is the friction, which takes place between the pile and the soil. Pile foundations can be categorized as bored and driven piles. Bored piles installed in sand are known to provide relatively low capacity as compared to driven piles under the same condition. This is due the effect of the pile driving process. The estimation of the shaft resistance of driven piles remains empirical at best. The changes in the in situ stress levels as a result of pile installation are quite often overestimated/underestimated leading to unsafe/uneconomic design of the foundations. The objective of this study is to examine the changes in the in situ stresses during the pile driving process, and accordingly to predict the pile capacity. In order to achieve these objectives, numerical model is developed to simulate the process of pile installation and link the cavity expansion to the pile installation and pile diameter. During this research program the changes in the soil mass due to pile installation will be recorded. Furthermore, the changes of the OCR around the pile will be examined and its effects on the earth pressure acting on the pile's shaft will be evaluated. Based on the results of the present investigation, design theory is proposed to account for the effect of pile diameter during installation in dry sand. In order to achieve these objectives, a numerical model utilizing the finite element method of analysis combined with the theory of cavity expansion is developed. This model is capable of predicting the magnitude and the distribution of the coefficient earth pressure acting on the pile's shaft and accordingly the overconsolidation ratio. Based on the result obtained from the numerical model, an analytical model was developed to incorporate the findings observed from the numerical model. The analytical model will be then presented in the form of design procedure and design charts for practical use. The theories developed herein compared well with the available laboratory and field experimental data.
"This volume contains 101 papers presented at the 8th International Conference on the Application of Stress Wave Theory to Piles, held in Lisbon, Portugal in 2008." "It is divided in 14 chapters according to the conference themes: Wave mechanics applied to pile engineering; Relationship between static resistance to driving and long-term static soil resistance; Case histories involving measurementand analysis of stress waves; Dynamic monitoring of driven piles; Dynamic soil-pile interaction models - numerical and physical modeling; High-strain dynamic test; Low-strain dynamic test; Rapid-load test; Monitoring and analysis of vibratory driven piles; Correlation of dynamic and static load tests; Quality assurance of deep foundations using dynamic methods; Incorporation of dynamic testing into design codes and testing standards; Ground vibrations induced by pile motions; Dynamic measurements in ground field testing." "This conference aims to contribute to a better and more efficient professional interaction between specialized contractors, designers and academicians. By joining the contribution of all of them it was possible to elucidate the today's state-of-the-art in science, technology and practice in the application of stress wave theory to piles."--BOOK JACKET.
Broadening the recommendations published by Jardine and Chow in 1996, this volume provides procedures that can be applied by geotechnical engineers, supported by worked examples for sands and clays. It also offers guidance on application to a range of pile types, geotechnical profiles and loading conditions.
Cone Penetration Testing 2018 contains the proceedings of the 4th International Symposium on Cone Penetration Testing (CPT’18, Delft, The Netherlands, 21-22 June 2018), and presents the latest developments relating to the use of cone penetration testing in geotechnical engineering. It focuses on the solution of geotechnical challenges using the cone penetration test (CPT), CPT add-on measurements and companion in-situ penetration tools (such as full flow and free fall penetrometers), with an emphasis on practical experience and application of research findings. The peer-reviewed papers have been authored by academics, researchers and practitioners from many countries worldwide and cover numerous important aspects, ranging from the development of innovative theoretical and numerical methods of interpretation, to real field applications. This is an Open Access ebook, and can be found on www.taylorfrancis.com.
[Truncated abstract] The axial performance of piles in sand remains an area of great uncertainty in geotechnical engineering. Over the years, database studies have shown that the existing method for offshore piles (e.g. API 2000) is unreliable. There is therefore a clear need for an improved predictive method, which incorporates the state-ofthe- art understanding of the underlying controlling mechanisms. This Thesis is dedicated to address the factors influencing the end bearing performance of displacement piles in siliceous sand with a view to proposing and justifying an improved design formulation. Firstly, a database of displacement pile load tests in sand with CPT data was compiled in collaboration with James Schneider (Schneider 2007). It features the widest database with also the latest available pile load test data (e.g. Euripides, Ras Tanajib, Drammen etc) in electronic form. Evaluation of the three new CPTbased methods (Fugro-05, ICP-05 & NGI-05) against this database has revealed a broadly similar predictive performance despite their end bearing formulations being remarkably different. This anomaly promoted the author to extend the database to include additional tests with base capacity measurements to form new base capacity databases for driven and jacked piles, which resulted in the UWA- 05 method for end bearing of displacement piles in sand. This method accounts for the pile effective area ratio, differentiates between driven and jacked piles, and employs a rational qc averaging technique. ... Field tests were performed in Shenton Park, Perth to supplement the database study and, in particular, to examine the effect of the incremental filling ratio (IFR). 10 open-ended and 2 closed-ended piles were tested in compression followed by tension. The test results provide strong support for the UWA-05 method for base capacity evaluation employing the CPT qc values and the effective area ratio. A series of jacked pile tests was carried out on the UWA beam centrifuge, to further explore the factors affecting pile base response. In total, four uniform and four layered centrifuge samples were prepared and tested at various stress levels and relative densities using three separate pile diameters. The resistance ratio (qb0.1/qc,avg) is found to be independent of the absolute pile diameter, effective stress and soil relative density. The tests in layered soil enabled quantification of the reduction in penetration resistance when a pile/cone approaches a weak layer and revealed the significant influence on base stiffness of underlying soft clay layers. The stiffness decay curves (G/GIN vs. w/D, where GIN is initial operational shear stiffness) measured in static load tests were found to vary with ratios of GIN/qc, while there was a unique relationship between G/GIN and qb/qc. A detailed parametric study was carried out (using the FE code PLAXIS) by idealising pile penetration using a spherical cavity expansion analogue in layered soil. The numerical predictions compare well with the centrifuge results and their generalization enabled guidelines to be established for end bearing in layered soil.