New Load Transfer Hyperbolic Model for Pile-Soil Interface and Negative Skin Friction on Single Piles Embedded in Soft Soils

2014 ◽  
Vol 14 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Weiping Cao ◽  
Yunmin Chen ◽  
W. E. Wolfe
Keyword(s):  
Skin Friction ◽  
Load Transfer ◽  
Hyperbolic Model ◽  
Soft Soils ◽  
Negative Skin Friction ◽  
Single Piles ◽  
Soil Interface

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.

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.

Analysis of Negative Skin-Friction on Single Piles by One-Dimensional Consolidation Model Test

2018 ◽  
Vol 16 (10) ◽  
pp. 1445-1461 ◽  
Author(s):  
Hyeong-Joo Kim ◽  
Jose Leo Mission ◽  
Tae-Woong Park ◽  
Peter Rey Dinoy
Keyword(s):  
Skin Friction ◽  
Model Test ◽  
Negative Skin Friction ◽  
One Dimensional ◽  
Consolidation Model ◽  
Single Piles

Performance of Floating Piles for Supporting Embankments in Soft Soils

2011 ◽  
Vol 105-107 ◽  
pp. 1433-1437
Author(s):  
Wei Ping Cao ◽  
Min Zhao
Keyword(s):  
Reinforced Concrete ◽  
Skin Friction ◽  
Axial Force ◽  
Soft Soils ◽  
Negative Skin Friction ◽  
Concrete Piles ◽  
Reinforced Concrete Piles ◽  
Soil Arch ◽  
Stress Concentration Ratio ◽  
Embankment Load

Reinforced concrete piles are often used to support highway embankments in soft soils. The performance of floating piles differs significantly from that of end-bearing piles. A numerical analysis was conducted to investigate the soil stress concentration ratio, pile and soil settlements, pile axial force, negative skin friction (NSF) and the location of the neutral plane (NP) during embankment filling and consolidation of soft soils when the soft soils is treated by using reinforced concrete floating piles. The results indicate that the pile axial force as well as negative skin friction is closely time dependent and increase much more quickly during the embankment filling than during the consolidation. The location of the NP exhibits a complicated variation as the pile head loads and the surcharge applied on the soft soils are varying with time. Most of the embankment load is born by pile for the existence of soil arch within the embankment.

Development of negative skin friction on driven piles in soft Bangkok clay

1992 ◽  
Vol 29 (3) ◽  
pp. 393-404 ◽  
Author(s):  
B. Indraratna ◽  
A. S. Balasubramaniam ◽  
P. Phamvan ◽  
Y. K. Wong
Keyword(s):  
Skin Friction ◽  
Prestressed Concrete ◽  
Load Transfer ◽  
Soft Clay ◽  
Driven Piles ◽  
Short Term ◽  
Negative Skin Friction ◽  
Pullout Tests ◽  
Pore Pressures

This paper describes the results of short-term pullout tests and long-term full-scale measurements of negative skin friction on driven piles in Bangkok subsoils. Two instrumented cylindrical (hollow) prestressed concrete piles were fully equipped with two independent load-measurement systems, load cells, and telltale rods. Pore pressures and ground movements in the vicinity of the piles were monitored throughout the period of investigation. The effect of bitumen coating on negative skin friction was also studied. The long-term behaviour of driven piles was compared with the estimated values obtained from short-term pullout tests and soil strength data. It was found that the negative skin friction can be predicted well by the effective stress approach using values of β between 0.1 and 0.2. The load–settlement and load–transfer behaviour were numerically modelled to acquire a more comprehensive understanding of negative skin friction developed on driven piles. A settlement-controlled concept is also introduced for piles subjected to negative skin friction, on the basis of these findings. Key words : consolidation, downdrag, driven pile, embankment, finite elements, pore pressures, pullout, settlements, soft clay.

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