scholarly journals Negative skin friction on piles based on finite strain consolidation theory and the nonlinear load transfer method

2009 ◽  
Vol 13 (3) ◽  
pp. 217-217
Author(s):  
Hyeong Joo Kim ◽  
Jose Leo C. Mission
Keyword(s):  
Skin Friction ◽  
Finite Strain ◽  
Load Transfer ◽  
Nonlinear Load ◽  
Negative Skin Friction ◽  
Consolidation Theory ◽  
Transfer Method ◽  
Load Transfer Method

Development of negative skin friction on single piles: uncoupled analysis based on nonlinear consolidation theory with finite strain and the load-transfer method

2011 ◽  
Vol 48 (6) ◽  
pp. 905-914 ◽  
Author(s):  
Hyeong-Joo Kim ◽  
Jose Leo C. Mission
Keyword(s):  
Skin Friction ◽  
Effective Stress ◽  
Finite Strain ◽  
Load Transfer ◽  
Negative Skin Friction ◽  
Consolidation Theory ◽  
Single Piles ◽  
Transfer Method ◽  
Load Transfer Method ◽  
Nonlinear Consolidation

The development of negative skin friction (NSF) on single piles is investigated based on an uncoupled method of analysis with the Mikasa (1963) generalized nonlinear consolidation theory in terms of finite strain and the nonlinear load-transfer method. Predicted results are compared with results based on the conventional linear consolidation theory with infinitesimal strains. It is found that predicted development of dragload using the conventional consolidation theory is slightly greater and conservative compared to that using the nonlinear consolidation theory based on effective stress (β method). Effective stress predictions using the conventional theory are larger due to the faster dissipation of excess pore pressures, with the assumption of constant coefficient of consolidation and permeability. However, since the relative displacements required to mobilize the ultimate skin friction are small, and piles are usually installed near the final stages of soil consolidation, the differences in the predictions for the development of dragload on piles between the two consolidation theories are overshadowed. Using the uncoupled model for pile NSF, it is therefore found that the most significant factor for the estimation of dragload and downdrag is the proper selection of the β value rather than the consolidation theory used.

Installation Engineering Challenges of the World's Heaviest Topside on Steel Substructure

2021 ◽  
Author(s):  
Prasad Kunnathully Prabhakaran ◽  
Cibu Varghese ◽  
Faris Ragheb Kamal
Keyword(s):  
Weight Control ◽  
Oil And Gas ◽  
Load Transfer ◽  
Development Project ◽  
Design Stage ◽  
Gas Treatment ◽  
Field Development ◽  
Gas Processing ◽  
Transfer Method ◽  
Load Transfer Method

Abstract As part of a green field development project for ADNOC offshore, NPCC here in after called as "contractor", successfully completed installation of an oil and gas processing super complex at offshore Abu Dhabi. This super complex consisted of four large interconnected platforms of different functionalities and an accommodation platform. Associated flare structures and interconnecting bridges were also installed as part of this project. Weights of the topsides in this project were varying from 7,000MT to a ∼32,000 MT. All these topsides were installed by float-over method using contractors own cargo /launch barge fleet. Gas treatment platform topside installed as part of the above project is the world's heaviest single-module topside Installed by float-over on a fixed steel jacket. Float-over is the process of installing the topside on a preinstalled jacket by ballasting and/or by other methods of load transfer such as hydraulic jacks. This installation method is widely used for heavy topsides, due to its cost effectiveness and efficiency. By float over installation method, the topside can be installed as a single integrated unit after completion of all hookup and commissioning works onshore. This paper outlines installation engineering challenges during EPC phase for the gas treatment platform topside. Design of this topside went through phenomenal changes in terms of its size and weight during EPC phase and posed several challenges to install this unit as a single module. This paper presents the installation method, and various parameters considered during installation and also includes discussion on selection of float-over barge, importance of weight control & layout design, finalization of topside support height on barge and installation aids. This paper also presents various installation engineering analyses required during design stage. Float-over installation of the gas treatment platform was carried out by the conventional load transfer method (by ballasting) and using normal spread mooring arrangement.

scholarly journals Mathematical Model and Analysis of Negative Skin Friction of Pile Group in Consolidating Soil

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Gangqiang Kong ◽  
Hanlong Liu ◽  
Qing Yang ◽  
Robert Y. Liang ◽  
Hang Zhou
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Skin Friction ◽  
Load Transfer ◽  
Pile Group ◽  
Soil Consolidation ◽  
Group Effect ◽  
Negative Skin Friction ◽  
Compressibility Coefficient ◽  
Consolidating Soil

In order to calculate negative skin friction (NSF) of pile group embedded in a consolidating soil, the dragload calculating formulas of single pile were established by considering Davis one-dimensional nonlinear consolidation soils settlement and hyperbolic load-transfer of pile-soil interface. Based on effective influence area theory, a simple semiempirical mathematical model of analysis for predicting the group effect of pile group under dragload was described. The accuracy and reliability of mathematical models built in this paper were verified by practical engineering comparative analysis. Case studies were studied, and the prediction values were found to be in good agreement with those of measured values. Then, the influences factors, such as, soil consolidation degree, the initial volume compressibility coefficient, and the stiffness of bearing soil, were analyzed and discussed. The results show that the mathematical models considering nonlinear soil consolidation and group effect can reflect the practical NSF of pile group effectively and accurately. The results of this paper can provide reference for practical pile group embedded in consolidating soil under NSF design and calculation.

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